diff --git a/packages/pigeon/CHANGELOG.md b/packages/pigeon/CHANGELOG.md
index 5bca85da4b69..6be42dca77c6 100644
--- a/packages/pigeon/CHANGELOG.md
+++ b/packages/pigeon/CHANGELOG.md
@@ -4,6 +4,7 @@
 * [front-end] Added a more explicit error for static fields.
 * [front-end] Added more errors for incorrect usage of Pigeon (previously they were just ignored).
 * Moved Pigeon to using a custom codec which allows collection types to contain custom classes.
+* Started allowing primitive data types as arguments and return types.
 
 ## 0.3.0
 
diff --git a/packages/pigeon/lib/dart_generator.dart b/packages/pigeon/lib/dart_generator.dart
index 8e6d59b994ee..c2311352b8a4 100644
--- a/packages/pigeon/lib/dart_generator.dart
+++ b/packages/pigeon/lib/dart_generator.dart
@@ -121,19 +121,14 @@ final BinaryMessenger$nullTag _binaryMessenger;
       }
       String argSignature = '';
       String sendArgument = 'null';
-      String? encodedDeclaration;
       if (func.argType != 'void') {
         argSignature = '${func.argType} arg';
-        sendArgument = 'encoded';
-        encodedDeclaration = 'final Object encoded = arg.encode();';
+        sendArgument = 'arg';
       }
       indent.write(
         'Future<${func.returnType}> ${func.name}($argSignature) async ',
       );
       indent.scoped('{', '}', () {
-        if (encodedDeclaration != null) {
-          indent.writeln(encodedDeclaration);
-        }
         final String channelName = makeChannelName(api, func);
         indent.writeln(
             'final BasicMessageChannel<Object$nullTag> channel = BasicMessageChannel<Object$nullTag>(');
@@ -144,7 +139,7 @@ final BinaryMessenger$nullTag _binaryMessenger;
         });
         final String returnStatement = func.returnType == 'void'
             ? '// noop'
-            : 'return ${func.returnType}.decode(replyMap[\'${Keys.result}\']$unwrapOperator);';
+            : 'return (replyMap[\'${Keys.result}\'] as ${func.returnType}$nullTag)$unwrapOperator;';
         indent.format('''
 final Map<Object$nullTag, Object$nullTag>$nullTag replyMap =\n\t\tawait channel.send($sendArgument) as Map<Object$nullTag, Object$nullTag>$nullTag;
 if (replyMap == null) {
@@ -237,7 +232,7 @@ void _writeFlutterApi(
                   'assert(message != null, \'Argument for $channelName was null. Expected $argType.\');',
                 );
                 indent.writeln(
-                  'final $argType input = $argType.decode(message$unwrapOperator);',
+                  'final $argType input = (message as $argType$nullTag)$unwrapOperator;',
                 );
                 call = 'api.${func.name}(input)';
               }
@@ -254,7 +249,7 @@ void _writeFlutterApi(
                 } else {
                   indent.writeln('final $returnType output = $call;');
                 }
-                const String returnExpression = 'output.encode()';
+                const String returnExpression = 'output';
                 final String returnStatement = isMockHandler
                     ? 'return <Object$nullTag, Object$nullTag>{\'${Keys.result}\': $returnExpression};'
                     : 'return $returnExpression;';
diff --git a/packages/pigeon/lib/generator_tools.dart b/packages/pigeon/lib/generator_tools.dart
index e5f07d9f45fd..560bcd184fbd 100644
--- a/packages/pigeon/lib/generator_tools.dart
+++ b/packages/pigeon/lib/generator_tools.dart
@@ -262,6 +262,20 @@ class EnumeratedClass {
   final int enumeration;
 }
 
+/// Supported basic datatypes.
+const List<String> validTypes = <String>[
+  'String',
+  'bool',
+  'int',
+  'double',
+  'Uint8List',
+  'Int32List',
+  'Int64List',
+  'Float64List',
+  'List',
+  'Map',
+];
+
 /// Custom codecs' custom types are enumerated from 255 down to this number to
 /// avoid collisions with the StandardMessageCodec.
 const int _minimumCodecFieldKey = 128;
@@ -274,8 +288,10 @@ Iterable<EnumeratedClass> getCodecClasses(Api api) sync* {
     names.add(method.returnType);
     names.add(method.argType);
   }
-  final List<String> sortedNames =
-      names.where((String element) => element != 'void').toList();
+  final List<String> sortedNames = names
+      .where((String element) =>
+          element != 'void' && !validTypes.contains(element))
+      .toList();
   sortedNames.sort();
   int enumeration = _minimumCodecFieldKey;
   const int maxCustomClassesPerApi = 255 - _minimumCodecFieldKey;
diff --git a/packages/pigeon/lib/java_generator.dart b/packages/pigeon/lib/java_generator.dart
index d53c8293c6ac..eae2cea23567 100644
--- a/packages/pigeon/lib/java_generator.dart
+++ b/packages/pigeon/lib/java_generator.dart
@@ -113,6 +113,22 @@ void _writeCodec(Indent indent, Api api) {
   });
 }
 
+/// This performs Dart to Java type conversions.  If performs a passthrough of
+/// the input if it can't be converted.
+// TODO(gaaclarke): Remove this method and unify it with `_javaTypeForDartType`.
+String _javaTypeForDartTypePassthrough(String type) {
+  const Map<String, String> map = <String, String>{
+    'int': 'Integer',
+    'bool': 'Boolean',
+    'double': 'Double',
+    'Int32List': 'int[]',
+    'Uint8List': 'byte[]',
+    'Int64List': 'long[]',
+    'Float64List': 'double[]',
+  };
+  return map[type] ?? type;
+}
+
 void _writeHostApi(Indent indent, Api api) {
   assert(api.location == ApiLocation.host);
 
@@ -121,11 +137,13 @@ void _writeHostApi(Indent indent, Api api) {
   indent.write('public interface ${api.name} ');
   indent.scoped('{', '}', () {
     for (final Method method in api.methods) {
-      final String returnType =
-          method.isAsynchronous ? 'void' : method.returnType;
+      final String argType = _javaTypeForDartTypePassthrough(method.argType);
+      final String returnType = method.isAsynchronous
+          ? 'void'
+          : _javaTypeForDartTypePassthrough(method.returnType);
       final List<String> argSignature = <String>[];
       if (method.argType != 'void') {
-        argSignature.add('${method.argType} arg');
+        argSignature.add('$argType arg');
       }
       if (method.isAsynchronous) {
         final String returnType =
@@ -162,21 +180,27 @@ static MessageCodec<Object> getCodec() {
           indent.scoped('{', '} else {', () {
             indent.write('channel.setMessageHandler((message, reply) -> ');
             indent.scoped('{', '});', () {
-              final String argType = method.argType;
-              final String returnType = method.returnType;
+              final String argType =
+                  _javaTypeForDartTypePassthrough(method.argType);
+              final String returnType =
+                  _javaTypeForDartTypePassthrough(method.returnType);
               indent.writeln('Map<String, Object> wrapped = new HashMap<>();');
               indent.write('try ');
               indent.scoped('{', '}', () {
                 final List<String> methodArgument = <String>[];
                 if (argType != 'void') {
                   indent.writeln('@SuppressWarnings("ConstantConditions")');
-                  indent.writeln(
-                      '$argType input = $argType.fromMap((Map<String, Object>)message);');
+                  indent.writeln('$argType input = ($argType)message;');
+                  indent.write('if (input == null) ');
+                  indent.scoped('{', '}', () {
+                    indent.writeln(
+                        'throw new NullPointerException("Message unexpectedly null.");');
+                  });
                   methodArgument.add('input');
                 }
                 if (method.isAsynchronous) {
                   final String resultValue =
-                      method.returnType == 'void' ? 'null' : 'result.toMap()';
+                      method.returnType == 'void' ? 'null' : 'result';
                   methodArgument.add(
                     'result -> { '
                     'wrapped.put("${Keys.result}", $resultValue); '
@@ -193,8 +217,7 @@ static MessageCodec<Object> getCodec() {
                   indent.writeln('wrapped.put("${Keys.result}", null);');
                 } else {
                   indent.writeln('$returnType output = $call;');
-                  indent.writeln(
-                      'wrapped.put("${Keys.result}", output.toMap());');
+                  indent.writeln('wrapped.put("${Keys.result}", output);');
                 }
               });
               indent.write('catch (Error | RuntimeException exception) ');
@@ -242,16 +265,18 @@ static MessageCodec<Object> getCodec() {
 ''');
     for (final Method func in api.methods) {
       final String channelName = makeChannelName(api, func);
-      final String returnType =
-          func.returnType == 'void' ? 'Void' : func.returnType;
+      final String returnType = func.returnType == 'void'
+          ? 'Void'
+          : _javaTypeForDartTypePassthrough(func.returnType);
+      final String argType = _javaTypeForDartTypePassthrough(func.argType);
       String sendArgument;
       if (func.argType == 'void') {
         indent.write('public void ${func.name}(Reply<$returnType> callback) ');
         sendArgument = 'null';
       } else {
         indent.write(
-            'public void ${func.name}(${func.argType} argInput, Reply<$returnType> callback) ');
-        sendArgument = 'inputMap';
+            'public void ${func.name}($argType argInput, Reply<$returnType> callback) ');
+        sendArgument = 'argInput';
       }
       indent.scoped('{', '}', () {
         indent.writeln('BasicMessageChannel<Object> channel =');
@@ -261,18 +286,13 @@ static MessageCodec<Object> getCodec() {
             'new BasicMessageChannel<>(binaryMessenger, "$channelName", getCodec());');
         indent.dec();
         indent.dec();
-        if (func.argType != 'void') {
-          indent.writeln('Map<String, Object> inputMap = argInput.toMap();');
-        }
         indent.write('channel.send($sendArgument, channelReply -> ');
         indent.scoped('{', '});', () {
           if (func.returnType == 'void') {
             indent.writeln('callback.reply(null);');
           } else {
-            indent.writeln('Map outputMap = (Map)channelReply;');
             indent.writeln('@SuppressWarnings("ConstantConditions")');
-            indent.writeln(
-                '${func.returnType} output = ${func.returnType}.fromMap(outputMap);');
+            indent.writeln('$returnType output = ($returnType)channelReply;');
             indent.writeln('callback.reply(output);');
           }
         });
diff --git a/packages/pigeon/lib/objc_generator.dart b/packages/pigeon/lib/objc_generator.dart
index c46708fbe391..77612a49854f 100644
--- a/packages/pigeon/lib/objc_generator.dart
+++ b/packages/pigeon/lib/objc_generator.dart
@@ -67,16 +67,16 @@ String _callbackForType(String dartType, String objcType) {
 }
 
 const Map<String, String> _objcTypeForDartTypeMap = <String, String>{
-  'bool': 'NSNumber *',
-  'int': 'NSNumber *',
-  'String': 'NSString *',
-  'double': 'NSNumber *',
-  'Uint8List': 'FlutterStandardTypedData *',
-  'Int32List': 'FlutterStandardTypedData *',
-  'Int64List': 'FlutterStandardTypedData *',
-  'Float64List': 'FlutterStandardTypedData *',
-  'List': 'NSArray *',
-  'Map': 'NSDictionary *',
+  'bool': 'NSNumber',
+  'int': 'NSNumber',
+  'String': 'NSString',
+  'double': 'NSNumber',
+  'Uint8List': 'FlutterStandardTypedData',
+  'Int32List': 'FlutterStandardTypedData',
+  'Int64List': 'FlutterStandardTypedData',
+  'Float64List': 'FlutterStandardTypedData',
+  'List': 'NSArray',
+  'Map': 'NSDictionary',
 };
 
 const Map<String, String> _propertyTypeForDartTypeMap = <String, String>{
@@ -92,8 +92,18 @@ const Map<String, String> _propertyTypeForDartTypeMap = <String, String>{
   'Map': 'strong',
 };
 
-String? _objcTypeForDartType(String type) {
-  return _objcTypeForDartTypeMap[type];
+String? _objcTypePtrForPrimitiveDartType(String type) {
+  return _objcTypeForDartTypeMap.containsKey(type)
+      ? '${_objcTypeForDartTypeMap[type]} *'
+      : null;
+}
+
+/// Returns the objc type for a dart [type], prepending the [classPrefix] for
+/// generated classes.  For example:
+/// _objcTypeForDartType(null, 'int') => 'NSNumber'.
+String _objcTypeForDartType(String? classPrefix, String type) {
+  final String? builtinObjcType = _objcTypeForDartTypeMap[type];
+  return builtinObjcType ?? _className(classPrefix, type);
 }
 
 String _propertyTypeForDartType(String type) {
@@ -112,7 +122,7 @@ void _writeClassDeclarations(
     indent.writeln('@interface ${_className(prefix, klass.name)} : NSObject');
     for (final Field field in klass.fields) {
       final HostDatatype hostDatatype = getHostDatatype(
-          field, classes, enums, _objcTypeForDartType,
+          field, classes, enums, _objcTypePtrForPrimitiveDartType,
           customResolver: enumNames.contains(field.dataType)
               ? (String x) => _className(prefix, x)
               : (String x) => '${_className(prefix, x)} *');
@@ -217,14 +227,16 @@ void _writeHostApiDeclaration(Indent indent, Api api, ObjcOptions options) {
   final String apiName = _className(options.prefix, api.name);
   indent.writeln('@protocol $apiName');
   for (final Method func in api.methods) {
-    final String returnTypeName = _className(options.prefix, func.returnType);
+    final String returnTypeName =
+        _objcTypeForDartType(options.prefix, func.returnType);
     if (func.isAsynchronous) {
       if (func.returnType == 'void') {
         if (func.argType == 'void') {
           indent.writeln(
               '-(void)${func.name}:(void(^)(FlutterError *_Nullable))completion;');
         } else {
-          final String argType = _className(options.prefix, func.argType);
+          final String argType =
+              _objcTypeForDartType(options.prefix, func.argType);
           indent.writeln(
               '-(void)${func.name}:(nullable $argType *)input completion:(void(^)(FlutterError *_Nullable))completion;');
         }
@@ -233,7 +245,8 @@ void _writeHostApiDeclaration(Indent indent, Api api, ObjcOptions options) {
           indent.writeln(
               '-(void)${func.name}:(void(^)($returnTypeName *_Nullable, FlutterError *_Nullable))completion;');
         } else {
-          final String argType = _className(options.prefix, func.argType);
+          final String argType =
+              _objcTypeForDartType(options.prefix, func.argType);
           indent.writeln(
               '-(void)${func.name}:(nullable $argType *)input completion:(void(^)($returnTypeName *_Nullable, FlutterError *_Nullable))completion;');
         }
@@ -245,7 +258,8 @@ void _writeHostApiDeclaration(Indent indent, Api api, ObjcOptions options) {
         indent.writeln(
             '-($returnType)${func.name}:(FlutterError *_Nullable *_Nonnull)error;');
       } else {
-        final String argType = _className(options.prefix, func.argType);
+        final String argType =
+            _objcTypeForDartType(options.prefix, func.argType);
         indent.writeln(
             '-($returnType)${func.name}:($argType*)input error:(FlutterError *_Nullable *_Nonnull)error;');
       }
@@ -264,12 +278,13 @@ void _writeFlutterApiDeclaration(Indent indent, Api api, ObjcOptions options) {
   indent.writeln(
       '- (instancetype)initWithBinaryMessenger:(id<FlutterBinaryMessenger>)binaryMessenger;');
   for (final Method func in api.methods) {
-    final String returnType = _className(options.prefix, func.returnType);
+    final String returnType =
+        _objcTypeForDartType(options.prefix, func.returnType);
     final String callbackType = _callbackForType(func.returnType, returnType);
     if (func.argType == 'void') {
       indent.writeln('- (void)${func.name}:($callbackType)completion;');
     } else {
-      final String argType = _className(options.prefix, func.argType);
+      final String argType = _objcTypeForDartType(options.prefix, func.argType);
       indent.writeln(
           '- (void)${func.name}:($argType*)input completion:($callbackType)completion;');
     }
@@ -386,13 +401,14 @@ void _writeHostApiSource(Indent indent, ObjcOptions options, Api api) {
               '[channel setMessageHandler:^(id _Nullable message, FlutterReply callback) ');
           indent.scoped('{', '}];', () {
             final String returnType =
-                _className(options.prefix, func.returnType);
+                _objcTypeForDartType(options.prefix, func.returnType);
             String syncCall;
             if (func.argType == 'void') {
               syncCall = '[api ${func.name}:&error]';
             } else {
-              final String argType = _className(options.prefix, func.argType);
-              indent.writeln('$argType *input = [$argType fromMap:message];');
+              final String argType =
+                  _objcTypeForDartType(options.prefix, func.argType);
+              indent.writeln('$argType *input = message;');
               syncCall = '[api ${func.name}:input error:&error]';
             }
             if (func.isAsynchronous) {
@@ -412,8 +428,7 @@ void _writeHostApiSource(Indent indent, ObjcOptions options, Api api) {
                   });
                 }
               } else {
-                const String callback =
-                    'callback(wrapResult([output toMap], error));';
+                const String callback = 'callback(wrapResult(output, error));';
                 if (func.argType == 'void') {
                   indent.writeScoped(
                       '[api ${func.name}:^($returnType *_Nullable output, FlutterError *_Nullable error) {',
@@ -435,7 +450,7 @@ void _writeHostApiSource(Indent indent, ObjcOptions options, Api api) {
                 indent.writeln('callback(wrapResult(nil, error));');
               } else {
                 indent.writeln('$returnType *output = $syncCall;');
-                indent.writeln('callback(wrapResult([output toMap], error));');
+                indent.writeln('callback(wrapResult(output, error));');
               }
             }
           });
@@ -470,7 +485,8 @@ void _writeFlutterApiSource(Indent indent, ObjcOptions options, Api api) {
   });
   indent.addln('');
   for (final Method func in api.methods) {
-    final String returnType = _className(options.prefix, func.returnType);
+    final String returnType =
+        _objcTypeForDartType(options.prefix, func.returnType);
     final String callbackType = _callbackForType(func.returnType, returnType);
 
     String sendArgument;
@@ -478,10 +494,10 @@ void _writeFlutterApiSource(Indent indent, ObjcOptions options, Api api) {
       indent.write('- (void)${func.name}:($callbackType)completion ');
       sendArgument = 'nil';
     } else {
-      final String argType = _className(options.prefix, func.argType);
+      final String argType = _objcTypeForDartType(options.prefix, func.argType);
       indent.write(
           '- (void)${func.name}:($argType*)input completion:($callbackType)completion ');
-      sendArgument = 'inputMap';
+      sendArgument = 'input';
     }
     indent.scoped('{', '}', () {
       indent.writeln('FlutterBasicMessageChannel *channel =');
@@ -494,17 +510,12 @@ void _writeFlutterApiSource(Indent indent, ObjcOptions options, Api api) {
           'codec:${_getCodecGetterName(options.prefix, api.name)}()];');
       indent.dec();
       indent.dec();
-      if (func.argType != 'void') {
-        indent.writeln('NSDictionary* inputMap = [input toMap];');
-      }
       indent.write('[channel sendMessage:$sendArgument reply:^(id reply) ');
       indent.scoped('{', '}];', () {
         if (func.returnType == 'void') {
           indent.writeln('completion(nil);');
         } else {
-          indent.writeln('NSDictionary* outputMap = reply;');
-          indent.writeln(
-              '$returnType * output = [$returnType fromMap:outputMap];');
+          indent.writeln('$returnType * output = reply;');
           indent.writeln('completion(output, nil);');
         }
       });
@@ -536,7 +547,7 @@ void generateObjcSource(ObjcOptions options, Root root, StringSink sink) {
   indent.addln('');
 
   indent.format('''
-static NSDictionary<NSString*, id>* wrapResult(NSDictionary *result, FlutterError *error) {
+static NSDictionary<NSString*, id>* wrapResult(id result, FlutterError *error) {
 \tNSDictionary *errorDict = (NSDictionary *)[NSNull null];
 \tif (error) {
 \t\terrorDict = @{
diff --git a/packages/pigeon/lib/pigeon_lib.dart b/packages/pigeon/lib/pigeon_lib.dart
index f04ae1dd3144..a1252226f29b 100644
--- a/packages/pigeon/lib/pigeon_lib.dart
+++ b/packages/pigeon/lib/pigeon_lib.dart
@@ -25,19 +25,6 @@ import 'ast.dart';
 import 'dart_generator.dart';
 import 'objc_generator.dart';
 
-const List<String> _validTypes = <String>[
-  'String',
-  'bool',
-  'int',
-  'double',
-  'Uint8List',
-  'Int32List',
-  'Int64List',
-  'Float64List',
-  'List',
-  'Map',
-];
-
 class _Asynchronous {
   const _Asynchronous();
 }
@@ -397,7 +384,7 @@ List<Error> _validateAst(Root root, String source) {
               'Unsupported datatype:"${field.dataType}" in class "${klass.name}". Generic fields aren\'t yet supported (https://github.com/flutter/flutter/issues/63468).',
           lineNumber: _calculateLineNumberNullable(source, field.offset),
         ));
-      } else if (!(_validTypes.contains(field.dataType) ||
+      } else if (!(validTypes.contains(field.dataType) ||
           customClasses.contains(field.dataType) ||
           customEnums.contains(field.dataType))) {
         result.add(Error(
@@ -413,28 +400,14 @@ List<Error> _validateAst(Root root, String source) {
       if (method.isReturnNullable) {
         result.add(Error(
           message:
-              'Nullable return types types aren\'t supported for Pigeon methods: "${method.argType}" in API: "${api.name}" method: "${method.name}',
+              'Nullable return types types aren\'t supported for Pigeon methods: "${method.argType}" in API: "${api.name}" method: "${method.name}"',
           lineNumber: _calculateLineNumberNullable(source, method.offset),
         ));
       }
       if (method.isArgNullable) {
         result.add(Error(
           message:
-              'Nullable argument types aren\'t supported for Pigeon methods: "${method.argType}" in API: "${api.name}" method: "${method.name}',
-          lineNumber: _calculateLineNumberNullable(source, method.offset),
-        ));
-      }
-      if (_validTypes.contains(method.argType)) {
-        result.add(Error(
-          message:
-              'Primitive argument types aren\'t yet supported (https://github.com/flutter/flutter/issues/66467): "${method.argType}" in API: "${api.name}" method: "${method.name}',
-          lineNumber: _calculateLineNumberNullable(source, method.offset),
-        ));
-      }
-      if (_validTypes.contains(method.returnType)) {
-        result.add(Error(
-          message:
-              'Primitive return types aren\'t yet supported (https://github.com/flutter/flutter/issues/66467): "${method.returnType}" in API: "${api.name}" method: "${method.name}',
+              'Nullable argument types aren\'t supported for Pigeon methods: "${method.argType}" in API: "${api.name}" method: "${method.name}"',
           lineNumber: _calculateLineNumberNullable(source, method.offset),
         ));
       }
@@ -502,7 +475,7 @@ class _RootBuilder extends dart_ast_visitor.RecursiveAstVisitor<Object?> {
           orElse: () => Class(name: '', fields: <Field>[]));
       for (final Field field in aClass.fields) {
         if (!referencedTypes.contains(field.dataType) &&
-            !_validTypes.contains(field.dataType)) {
+            !validTypes.contains(field.dataType)) {
           referencedTypes.add(field.dataType);
           classesToCheck.add(field.dataType);
         }
diff --git a/packages/pigeon/pigeons/flutter_unittests.dart b/packages/pigeon/pigeons/flutter_unittests.dart
index cb99095c33ff..de66fed79f91 100644
--- a/packages/pigeon/pigeons/flutter_unittests.dart
+++ b/packages/pigeon/pigeons/flutter_unittests.dart
@@ -28,4 +28,5 @@ abstract class Api {
   SearchReply search(SearchRequest request);
   SearchReplies doSearches(SearchRequests request);
   SearchRequests echo(SearchRequests requests);
+  int anInt(int value);
 }
diff --git a/packages/pigeon/pigeons/primitive.dart b/packages/pigeon/pigeons/primitive.dart
new file mode 100644
index 000000000000..2b453532b084
--- /dev/null
+++ b/packages/pigeon/pigeons/primitive.dart
@@ -0,0 +1,31 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:pigeon/pigeon.dart';
+
+@HostApi()
+abstract class PrimitiveHostApi {
+  int anInt(int value);
+  bool aBool(bool value);
+  String aString(String value);
+  double aDouble(double value);
+  // ignore: always_specify_types
+  Map aMap(Map value);
+  // ignore: always_specify_types
+  List aList(List value);
+  Int32List anInt32List(Int32List value);
+}
+
+@FlutterApi()
+abstract class PrimitiveFlutterApi {
+  int anInt(int value);
+  bool aBool(bool value);
+  String aString(String value);
+  double aDouble(double value);
+  // ignore: always_specify_types
+  Map aMap(Map value);
+  // ignore: always_specify_types
+  List aList(List value);
+  Int32List anInt32List(Int32List value);
+}
diff --git a/packages/pigeon/platform_tests/android_unit_tests/android/.project b/packages/pigeon/platform_tests/android_unit_tests/android/.project
new file mode 100644
index 000000000000..fe67538a518f
--- /dev/null
+++ b/packages/pigeon/platform_tests/android_unit_tests/android/.project
@@ -0,0 +1,28 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>android_</name>
+	<comment>Project android_ created by Buildship.</comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.buildship.core.gradleprojectbuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.buildship.core.gradleprojectnature</nature>
+	</natures>
+	<filteredResources>
+		<filter>
+			<id>1624921942866</id>
+			<name></name>
+			<type>30</type>
+			<matcher>
+				<id>org.eclipse.core.resources.regexFilterMatcher</id>
+				<arguments>node_modules|.git|__CREATED_BY_JAVA_LANGUAGE_SERVER__</arguments>
+			</matcher>
+		</filter>
+	</filteredResources>
+</projectDescription>
diff --git a/packages/pigeon/platform_tests/android_unit_tests/android/.settings/org.eclipse.buildship.core.prefs b/packages/pigeon/platform_tests/android_unit_tests/android/.settings/org.eclipse.buildship.core.prefs
new file mode 100644
index 000000000000..51db0abebef0
--- /dev/null
+++ b/packages/pigeon/platform_tests/android_unit_tests/android/.settings/org.eclipse.buildship.core.prefs
@@ -0,0 +1,13 @@
+arguments=
+auto.sync=false
+build.scans.enabled=false
+connection.gradle.distribution=GRADLE_DISTRIBUTION(WRAPPER)
+connection.project.dir=
+eclipse.preferences.version=1
+gradle.user.home=
+java.home=/Library/Java/JavaVirtualMachines/jdk-11-latest/Contents/Home
+jvm.arguments=
+offline.mode=false
+override.workspace.settings=true
+show.console.view=true
+show.executions.view=true
diff --git a/packages/pigeon/platform_tests/android_unit_tests/android/app/src/test/java/com/example/android_unit_tests/PigeonTest.java b/packages/pigeon/platform_tests/android_unit_tests/android/app/src/test/java/com/example/android_unit_tests/PigeonTest.java
index 24b5724b2604..196871dc9c4b 100644
--- a/packages/pigeon/platform_tests/android_unit_tests/android/app/src/test/java/com/example/android_unit_tests/PigeonTest.java
+++ b/packages/pigeon/platform_tests/android_unit_tests/android/app/src/test/java/com/example/android_unit_tests/PigeonTest.java
@@ -9,15 +9,12 @@
 
 import io.flutter.plugin.common.BinaryMessenger;
 import io.flutter.plugin.common.MessageCodec;
-import io.flutter.plugin.common.StandardMessageCodec;
 import java.nio.ByteBuffer;
 import java.util.Map;
 import org.junit.Test;
 import org.mockito.ArgumentCaptor;
 
 public class PigeonTest {
-  private MessageCodec<Object> codec = StandardMessageCodec.INSTANCE;
-
   @Test
   public void toMapAndBack() {
     Pigeon.SetRequest request = new Pigeon.SetRequest();
@@ -62,6 +59,7 @@ public void errorMessage() {
     ArgumentCaptor<BinaryMessenger.BinaryMessageHandler> handler =
         ArgumentCaptor.forClass(BinaryMessenger.BinaryMessageHandler.class);
     verify(binaryMessenger).setMessageHandler(anyString(), handler.capture());
+    MessageCodec<Object> codec = Pigeon.Api.getCodec();
     ByteBuffer message = codec.encodeMessage(null);
     handler
         .getValue()
@@ -86,7 +84,8 @@ public void callsVoidMethod() {
     Pigeon.SetRequest request = new Pigeon.SetRequest();
     request.setValue(1234l);
     request.setState(Pigeon.LoadingState.complete);
-    ByteBuffer message = codec.encodeMessage(request.toMap());
+    MessageCodec<Object> codec = Pigeon.Api.getCodec();
+    ByteBuffer message = codec.encodeMessage(request);
     message.rewind();
     handler
         .getValue()
diff --git a/packages/pigeon/platform_tests/android_unit_tests/android/app/src/test/java/com/example/android_unit_tests/PrimitiveTest.java b/packages/pigeon/platform_tests/android_unit_tests/android/app/src/test/java/com/example/android_unit_tests/PrimitiveTest.java
new file mode 100644
index 000000000000..36ce51cd35a0
--- /dev/null
+++ b/packages/pigeon/platform_tests/android_unit_tests/android/app/src/test/java/com/example/android_unit_tests/PrimitiveTest.java
@@ -0,0 +1,117 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package com.example.android_unit_tests;
+
+import static org.junit.Assert.*;
+import static org.mockito.Mockito.*;
+
+import com.example.android_unit_tests.Primitive.PrimitiveFlutterApi;
+import io.flutter.plugin.common.BinaryMessenger;
+import java.nio.ByteBuffer;
+import java.util.Collections;
+import java.util.List;
+import java.util.Map;
+import org.junit.Test;
+
+public class PrimitiveTest {
+  private static BinaryMessenger makeMockBinaryMessenger() {
+    BinaryMessenger binaryMessenger = mock(BinaryMessenger.class);
+    doAnswer(
+            invocation -> {
+              ByteBuffer message = invocation.getArgument(1);
+              BinaryMessenger.BinaryReply reply = invocation.getArgument(2);
+              message.position(0);
+              reply.reply(message);
+              return null;
+            })
+        .when(binaryMessenger)
+        .send(anyString(), any(), any());
+    return binaryMessenger;
+  }
+
+  @Test
+  public void primitiveInt() {
+    BinaryMessenger binaryMessenger = makeMockBinaryMessenger();
+    PrimitiveFlutterApi api = new PrimitiveFlutterApi(binaryMessenger);
+    boolean[] didCall = {false};
+    api.anInt(
+        1,
+        (Integer result) -> {
+          didCall[0] = true;
+          assertEquals(result, (Integer) 1);
+        });
+    assertTrue(didCall[0]);
+  }
+
+  @Test
+  public void primitiveBool() {
+    BinaryMessenger binaryMessenger = makeMockBinaryMessenger();
+    PrimitiveFlutterApi api = new PrimitiveFlutterApi(binaryMessenger);
+    boolean[] didCall = {false};
+    api.aBool(
+        true,
+        (Boolean result) -> {
+          didCall[0] = true;
+          assertEquals(result, (Boolean) true);
+        });
+    assertTrue(didCall[0]);
+  }
+
+  @Test
+  public void primitiveString() {
+    BinaryMessenger binaryMessenger = makeMockBinaryMessenger();
+    PrimitiveFlutterApi api = new PrimitiveFlutterApi(binaryMessenger);
+    boolean[] didCall = {false};
+    api.aString(
+        "hello",
+        (String result) -> {
+          didCall[0] = true;
+          assertEquals(result, "hello");
+        });
+    assertTrue(didCall[0]);
+  }
+
+  @Test
+  public void primitiveDouble() {
+    BinaryMessenger binaryMessenger = makeMockBinaryMessenger();
+    PrimitiveFlutterApi api = new PrimitiveFlutterApi(binaryMessenger);
+    boolean[] didCall = {false};
+    api.aDouble(
+        1.5,
+        (Double result) -> {
+          didCall[0] = true;
+          assertEquals(result, 1.5, 0.01);
+        });
+    assertTrue(didCall[0]);
+  }
+
+  @Test
+  public void primitiveMap() {
+    BinaryMessenger binaryMessenger = makeMockBinaryMessenger();
+    PrimitiveFlutterApi api = new PrimitiveFlutterApi(binaryMessenger);
+    boolean[] didCall = {false};
+    api.aMap(
+        Collections.singletonMap("hello", 1),
+        (Map result) -> {
+          didCall[0] = true;
+          assertEquals(result, Collections.singletonMap("hello", 1));
+        });
+    assertTrue(didCall[0]);
+  }
+
+  @Test
+  public void primitiveList() {
+    BinaryMessenger binaryMessenger = makeMockBinaryMessenger();
+    PrimitiveFlutterApi api = new PrimitiveFlutterApi(binaryMessenger);
+    boolean[] didCall = {false};
+    api.aList(
+        Collections.singletonList("hello"),
+        (List result) -> {
+          didCall[0] = true;
+          assertEquals(result, Collections.singletonList("hello"));
+        });
+    assertTrue(didCall[0]);
+  }
+}
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/all_datatypes.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/all_datatypes.dart
index 5ad97e5a78b8..09db4570911d 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/all_datatypes.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/all_datatypes.dart
@@ -60,7 +60,7 @@ class _HostEverythingCodec extends StandardMessageCodec {
   @override
   void writeValue(WriteBuffer buffer, Object? value) {
     if (value is Everything) {
-      buffer.putUint8(255);
+      buffer.putUint8(128);
       writeValue(buffer, value.encode());
     } else {
       super.writeValue(buffer, value);
@@ -70,7 +70,7 @@ class _HostEverythingCodec extends StandardMessageCodec {
   @override
   Object? readValueOfType(int type, ReadBuffer buffer) {
     switch (type) {
-      case 255:
+      case 128:
         return Everything.decode(readValue(buffer)!);
 
       default:
@@ -111,17 +111,16 @@ class HostEverything {
         details: error['details'],
       );
     } else {
-      return Everything.decode(replyMap['result']!);
+      return (replyMap['result'] as Everything?)!;
     }
   }
 
   Future<Everything> echo(Everything arg) async {
-    final Object encoded = arg.encode();
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
         'dev.flutter.pigeon.HostEverything.echo', codec,
         binaryMessenger: _binaryMessenger);
     final Map<Object?, Object?>? replyMap =
-        await channel.send(encoded) as Map<Object?, Object?>?;
+        await channel.send(arg) as Map<Object?, Object?>?;
     if (replyMap == null) {
       throw PlatformException(
         code: 'channel-error',
@@ -137,7 +136,7 @@ class HostEverything {
         details: error['details'],
       );
     } else {
-      return Everything.decode(replyMap['result']!);
+      return (replyMap['result'] as Everything?)!;
     }
   }
 }
@@ -147,7 +146,7 @@ class _FlutterEverythingCodec extends StandardMessageCodec {
   @override
   void writeValue(WriteBuffer buffer, Object? value) {
     if (value is Everything) {
-      buffer.putUint8(255);
+      buffer.putUint8(128);
       writeValue(buffer, value.encode());
     } else {
       super.writeValue(buffer, value);
@@ -157,7 +156,7 @@ class _FlutterEverythingCodec extends StandardMessageCodec {
   @override
   Object? readValueOfType(int type, ReadBuffer buffer) {
     switch (type) {
-      case 255:
+      case 128:
         return Everything.decode(readValue(buffer)!);
 
       default:
@@ -181,7 +180,7 @@ abstract class FlutterEverything {
         channel.setMessageHandler((Object? message) async {
           // ignore message
           final Everything output = api.giveMeEverything();
-          return output.encode();
+          return output;
         });
       }
     }
@@ -194,9 +193,9 @@ abstract class FlutterEverything {
         channel.setMessageHandler((Object? message) async {
           assert(message != null,
               'Argument for dev.flutter.pigeon.FlutterEverything.echo was null. Expected Everything.');
-          final Everything input = Everything.decode(message!);
+          final Everything input = (message as Everything?)!;
           final Everything output = api.echo(input);
-          return output.encode();
+          return output;
         });
       }
     }
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_safe_pigeon.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_safe_pigeon.dart
index 5445ab22559e..044bd03e80ee 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_safe_pigeon.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/lib/null_safe_pigeon.dart
@@ -81,16 +81,16 @@ class _ApiCodec extends StandardMessageCodec {
   @override
   void writeValue(WriteBuffer buffer, Object? value) {
     if (value is SearchReplies) {
-      buffer.putUint8(255);
+      buffer.putUint8(128);
       writeValue(buffer, value.encode());
     } else if (value is SearchReply) {
-      buffer.putUint8(254);
+      buffer.putUint8(129);
       writeValue(buffer, value.encode());
     } else if (value is SearchRequest) {
-      buffer.putUint8(253);
+      buffer.putUint8(130);
       writeValue(buffer, value.encode());
     } else if (value is SearchRequests) {
-      buffer.putUint8(252);
+      buffer.putUint8(131);
       writeValue(buffer, value.encode());
     } else {
       super.writeValue(buffer, value);
@@ -100,16 +100,16 @@ class _ApiCodec extends StandardMessageCodec {
   @override
   Object? readValueOfType(int type, ReadBuffer buffer) {
     switch (type) {
-      case 255:
+      case 128:
         return SearchReplies.decode(readValue(buffer)!);
 
-      case 254:
+      case 129:
         return SearchReply.decode(readValue(buffer)!);
 
-      case 253:
+      case 130:
         return SearchRequest.decode(readValue(buffer)!);
 
-      case 252:
+      case 131:
         return SearchRequests.decode(readValue(buffer)!);
 
       default:
@@ -129,12 +129,11 @@ class Api {
   static const MessageCodec<Object?> codec = _ApiCodec();
 
   Future<SearchReply> search(SearchRequest arg) async {
-    final Object encoded = arg.encode();
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
         'dev.flutter.pigeon.Api.search', codec,
         binaryMessenger: _binaryMessenger);
     final Map<Object?, Object?>? replyMap =
-        await channel.send(encoded) as Map<Object?, Object?>?;
+        await channel.send(arg) as Map<Object?, Object?>?;
     if (replyMap == null) {
       throw PlatformException(
         code: 'channel-error',
@@ -150,17 +149,16 @@ class Api {
         details: error['details'],
       );
     } else {
-      return SearchReply.decode(replyMap['result']!);
+      return (replyMap['result'] as SearchReply?)!;
     }
   }
 
   Future<SearchReplies> doSearches(SearchRequests arg) async {
-    final Object encoded = arg.encode();
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
         'dev.flutter.pigeon.Api.doSearches', codec,
         binaryMessenger: _binaryMessenger);
     final Map<Object?, Object?>? replyMap =
-        await channel.send(encoded) as Map<Object?, Object?>?;
+        await channel.send(arg) as Map<Object?, Object?>?;
     if (replyMap == null) {
       throw PlatformException(
         code: 'channel-error',
@@ -176,17 +174,16 @@ class Api {
         details: error['details'],
       );
     } else {
-      return SearchReplies.decode(replyMap['result']!);
+      return (replyMap['result'] as SearchReplies?)!;
     }
   }
 
   Future<SearchRequests> echo(SearchRequests arg) async {
-    final Object encoded = arg.encode();
     final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
         'dev.flutter.pigeon.Api.echo', codec,
         binaryMessenger: _binaryMessenger);
     final Map<Object?, Object?>? replyMap =
-        await channel.send(encoded) as Map<Object?, Object?>?;
+        await channel.send(arg) as Map<Object?, Object?>?;
     if (replyMap == null) {
       throw PlatformException(
         code: 'channel-error',
@@ -202,7 +199,32 @@ class Api {
         details: error['details'],
       );
     } else {
-      return SearchRequests.decode(replyMap['result']!);
+      return (replyMap['result'] as SearchRequests?)!;
+    }
+  }
+
+  Future<int> anInt(int arg) async {
+    final BasicMessageChannel<Object?> channel = BasicMessageChannel<Object?>(
+        'dev.flutter.pigeon.Api.anInt', codec,
+        binaryMessenger: _binaryMessenger);
+    final Map<Object?, Object?>? replyMap =
+        await channel.send(arg) as Map<Object?, Object?>?;
+    if (replyMap == null) {
+      throw PlatformException(
+        code: 'channel-error',
+        message: 'Unable to establish connection on channel.',
+        details: null,
+      );
+    } else if (replyMap['error'] != null) {
+      final Map<Object?, Object?> error =
+          (replyMap['error'] as Map<Object?, Object?>?)!;
+      throw PlatformException(
+        code: (error['code'] as String?)!,
+        message: error['message'] as String?,
+        details: error['details'],
+      );
+    } else {
+      return (replyMap['result'] as int?)!;
     }
   }
 }
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/all_datatypes_test.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/all_datatypes_test.dart
index b886c77753f8..7061fb8fa47a 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/all_datatypes_test.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/all_datatypes_test.dart
@@ -18,9 +18,9 @@ void main() {
     final BinaryMessenger mockMessenger = MockBinaryMessenger();
     when(mockMessenger.send('dev.flutter.pigeon.HostEverything.echo', any))
         .thenAnswer((Invocation realInvocation) async {
-      const StandardMessageCodec codec = StandardMessageCodec();
+      const MessageCodec<Object?> codec = HostEverything.codec;
       final Object input =
-          codec.decodeMessage(realInvocation.positionalArguments[1]);
+          codec.decodeMessage(realInvocation.positionalArguments[1])!;
       return codec.encodeMessage(<String, Object>{'result': input});
     });
     final HostEverything api = HostEverything(binaryMessenger: mockMessenger);
@@ -53,7 +53,7 @@ void main() {
     final BinaryMessenger mockMessenger = MockBinaryMessenger();
     when(mockMessenger.send('dev.flutter.pigeon.HostEverything.echo', any))
         .thenAnswer((Invocation realInvocation) async {
-      final MessageCodec<Object?> codec = HostEverything.codec;
+      const MessageCodec<Object?> codec = HostEverything.codec;
       final Object? input =
           codec.decodeMessage(realInvocation.positionalArguments[1]);
       return codec.encodeMessage(<String, Object>{'result': input!});
diff --git a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/null_safe_test.dart b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/null_safe_test.dart
index 769625c3d523..08809d56245b 100644
--- a/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/null_safe_test.dart
+++ b/packages/pigeon/platform_tests/flutter_null_safe_unit_tests/test/null_safe_test.dart
@@ -38,8 +38,8 @@ void main() {
     final SearchReply reply = SearchReply()..result = 'ho';
     final BinaryMessenger mockMessenger = MockBinaryMessenger();
     final Completer<ByteData?> completer = Completer<ByteData?>();
-    completer.complete(
-        Api.codec.encodeMessage(<String, Object>{'result': reply.encode()}));
+    completer
+        .complete(Api.codec.encodeMessage(<String, Object>{'result': reply}));
     final Future<ByteData?> sendResult = completer.future;
     when(mockMessenger.send('dev.flutter.pigeon.Api.search', any))
         .thenAnswer((Invocation realInvocation) => sendResult);
@@ -66,4 +66,19 @@ void main() {
     expect(echo.requests!.length, 1);
     expect((echo.requests![0] as SearchRequest?)!.query, 'hey');
   });
+
+  test('primiative datatypes', () async {
+    final BinaryMessenger mockMessenger = MockBinaryMessenger();
+    when(mockMessenger.send('dev.flutter.pigeon.Api.anInt', any))
+        .thenAnswer((Invocation realInvocation) async {
+      final MessageCodec<Object?> codec = Api.codec;
+      final Object? input =
+          codec.decodeMessage(realInvocation.positionalArguments[1]);
+      final int result = (input as int?)! + 1;
+      return codec.encodeMessage(<String, Object>{'result': result});
+    });
+    final Api api = Api(binaryMessenger: mockMessenger);
+    final int result = await api.anInt(1);
+    expect(result, 2);
+  });
 }
diff --git a/packages/pigeon/platform_tests/ios_unit_tests/ios/Flutter/AppFrameworkInfo.plist b/packages/pigeon/platform_tests/ios_unit_tests/ios/Flutter/AppFrameworkInfo.plist
index 6b4c0f78a785..f2872cf474ee 100644
--- a/packages/pigeon/platform_tests/ios_unit_tests/ios/Flutter/AppFrameworkInfo.plist
+++ b/packages/pigeon/platform_tests/ios_unit_tests/ios/Flutter/AppFrameworkInfo.plist
@@ -21,6 +21,6 @@
   <key>CFBundleVersion</key>
   <string>1.0</string>
   <key>MinimumOSVersion</key>
-  <string>8.0</string>
+  <string>9.0</string>
 </dict>
 </plist>
diff --git a/packages/pigeon/platform_tests/ios_unit_tests/ios/Runner.xcodeproj/project.pbxproj b/packages/pigeon/platform_tests/ios_unit_tests/ios/Runner.xcodeproj/project.pbxproj
index 1e359150faa8..43466c9f1589 100644
--- a/packages/pigeon/platform_tests/ios_unit_tests/ios/Runner.xcodeproj/project.pbxproj
+++ b/packages/pigeon/platform_tests/ios_unit_tests/ios/Runner.xcodeproj/project.pbxproj
@@ -8,6 +8,8 @@
 
 /* Begin PBXBuildFile section */
 		0D50127523FF75B100CD5B95 /* RunnerTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 0D50127423FF75B100CD5B95 /* RunnerTests.m */; };
+		0D6FD3C526A76D400046D8BD /* primitive.gen.m in Sources */ = {isa = PBXBuildFile; fileRef = 0D6FD3C426A76D400046D8BD /* primitive.gen.m */; };
+		0D6FD3C726A777C00046D8BD /* PrimitiveTest.m in Sources */ = {isa = PBXBuildFile; fileRef = 0D6FD3C626A777C00046D8BD /* PrimitiveTest.m */; };
 		0D7A910A268D4A050056B5E1 /* ListTest.m in Sources */ = {isa = PBXBuildFile; fileRef = 0D7A9109268D4A050056B5E1 /* ListTest.m */; };
 		0D7A910D268E5D700056B5E1 /* all_void.gen.m in Sources */ = {isa = PBXBuildFile; fileRef = 0D7A910C268E5D700056B5E1 /* all_void.gen.m */; };
 		0D8C35EB25D45A7900B76435 /* AsyncHandlersTest.m in Sources */ = {isa = PBXBuildFile; fileRef = 0D8C35EA25D45A7900B76435 /* AsyncHandlersTest.m */; };
@@ -60,6 +62,9 @@
 		0D50127223FF75B100CD5B95 /* RunnerTests.xctest */ = {isa = PBXFileReference; explicitFileType = wrapper.cfbundle; includeInIndex = 0; path = RunnerTests.xctest; sourceTree = BUILT_PRODUCTS_DIR; };
 		0D50127423FF75B100CD5B95 /* RunnerTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = RunnerTests.m; sourceTree = "<group>"; };
 		0D50127623FF75B100CD5B95 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
+		0D6FD3C326A76D400046D8BD /* primitive.gen.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = primitive.gen.h; sourceTree = "<group>"; };
+		0D6FD3C426A76D400046D8BD /* primitive.gen.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = primitive.gen.m; sourceTree = "<group>"; };
+		0D6FD3C626A777C00046D8BD /* PrimitiveTest.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = PrimitiveTest.m; sourceTree = "<group>"; };
 		0D7A9109268D4A050056B5E1 /* ListTest.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = ListTest.m; sourceTree = "<group>"; };
 		0D7A910B268E5D700056B5E1 /* all_void.gen.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = all_void.gen.h; sourceTree = "<group>"; };
 		0D7A910C268E5D700056B5E1 /* all_void.gen.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = all_void.gen.m; sourceTree = "<group>"; };
@@ -133,6 +138,7 @@
 				0DF4E5C7266ED80900AEA855 /* EchoMessenger.m */,
 				0DF4E5CA266FDAE300AEA855 /* EnumTest.m */,
 				0D7A9109268D4A050056B5E1 /* ListTest.m */,
+				0D6FD3C626A777C00046D8BD /* PrimitiveTest.m */,
 			);
 			path = RunnerTests;
 			sourceTree = "<group>";
@@ -170,6 +176,8 @@
 		97C146F01CF9000F007C117D /* Runner */ = {
 			isa = PBXGroup;
 			children = (
+				0D6FD3C326A76D400046D8BD /* primitive.gen.h */,
+				0D6FD3C426A76D400046D8BD /* primitive.gen.m */,
 				0D7A910B268E5D700056B5E1 /* all_void.gen.h */,
 				0D7A910C268E5D700056B5E1 /* all_void.gen.m */,
 				0DD2E6AA2684031300A7D764 /* all_datatypes.gen.h */,
@@ -354,6 +362,7 @@
 				0DF4E5C8266ED80900AEA855 /* EchoMessenger.m in Sources */,
 				0DF4E5CB266FDAE300AEA855 /* EnumTest.m in Sources */,
 				0D8C35EB25D45A7900B76435 /* AsyncHandlersTest.m in Sources */,
+				0D6FD3C726A777C00046D8BD /* PrimitiveTest.m in Sources */,
 				0D7A910A268D4A050056B5E1 /* ListTest.m in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
@@ -370,6 +379,7 @@
 				0DD2E6C32684031300A7D764 /* void_arg_flutter.gen.m in Sources */,
 				0DD2E6C22684031300A7D764 /* voidflutter.gen.m in Sources */,
 				0DD2E6C02684031300A7D764 /* all_datatypes.gen.m in Sources */,
+				0D6FD3C526A76D400046D8BD /* primitive.gen.m in Sources */,
 				97C146F31CF9000F007C117D /* main.m in Sources */,
 				0DD2E6BC2684031300A7D764 /* host2flutter.gen.m in Sources */,
 				0DD2E6BE2684031300A7D764 /* message.gen.m in Sources */,
@@ -517,7 +527,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;
@@ -596,7 +606,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = YES;
 				ONLY_ACTIVE_ARCH = YES;
 				SDKROOT = iphoneos;
@@ -645,7 +655,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 8.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				SDKROOT = iphoneos;
 				SUPPORTED_PLATFORMS = iphoneos;
diff --git a/packages/pigeon/platform_tests/ios_unit_tests/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist b/packages/pigeon/platform_tests/ios_unit_tests/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
new file mode 100644
index 000000000000..18d981003d68
--- /dev/null
+++ b/packages/pigeon/platform_tests/ios_unit_tests/ios/Runner.xcodeproj/project.xcworkspace/xcshareddata/IDEWorkspaceChecks.plist
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>IDEDidComputeMac32BitWarning</key>
+	<true/>
+</dict>
+</plist>
diff --git a/packages/pigeon/platform_tests/ios_unit_tests/ios/RunnerTests/AsyncHandlersTest.m b/packages/pigeon/platform_tests/ios_unit_tests/ios/RunnerTests/AsyncHandlersTest.m
index 88214ae9f309..83ecd790a15f 100644
--- a/packages/pigeon/platform_tests/ios_unit_tests/ios/RunnerTests/AsyncHandlersTest.m
+++ b/packages/pigeon/platform_tests/ios_unit_tests/ios/RunnerTests/AsyncHandlersTest.m
@@ -8,24 +8,25 @@
 
 ///////////////////////////////////////////////////////////////////////////////////////////
 @interface Value ()
-+ (Value*)fromMap:(NSDictionary*)dict;
-- (NSDictionary*)toMap;
++ (Value *)fromMap:(NSDictionary *)dict;
+- (NSDictionary *)toMap;
 @end
 
 ///////////////////////////////////////////////////////////////////////////////////////////
 @interface MockBinaryMessenger : NSObject<FlutterBinaryMessenger>
-@property(nonatomic, copy) NSNumber* result;
-@property(nonatomic, retain) FlutterStandardMessageCodec* codec;
-@property(nonatomic, retain) NSMutableDictionary<NSString*, FlutterBinaryMessageHandler>* handlers;
+@property(nonatomic, copy) NSNumber *result;
+@property(nonatomic, retain) NSObject<FlutterMessageCodec> *codec;
+@property(nonatomic, retain) NSMutableDictionary<NSString *, FlutterBinaryMessageHandler> *handlers;
+- (instancetype)init NS_UNAVAILABLE;
 @end
 
 ///////////////////////////////////////////////////////////////////////////////////////////
 @implementation MockBinaryMessenger
 
-- (instancetype)init {
+- (instancetype)initWithCodec:(NSObject<FlutterMessageCodec> *)codec {
   self = [super init];
   if (self) {
-    _codec = [FlutterStandardMessageCodec sharedInstance];
+    _codec = codec;
     _handlers = [[NSMutableDictionary alloc] init];
   }
   return self;
@@ -34,21 +35,20 @@ - (instancetype)init {
 - (void)cleanupConnection:(FlutterBinaryMessengerConnection)connection {
 }
 
-- (void)sendOnChannel:(nonnull NSString*)channel message:(NSData* _Nullable)message {
+- (void)sendOnChannel:(nonnull NSString *)channel message:(NSData *_Nullable)message {
 }
 
-- (void)sendOnChannel:(nonnull NSString*)channel
-              message:(NSData* _Nullable)message
+- (void)sendOnChannel:(nonnull NSString *)channel
+              message:(NSData *_Nullable)message
           binaryReply:(FlutterBinaryReply _Nullable)callback {
   if (self.result) {
-    Value* output = [[Value alloc] init];
+    Value *output = [[Value alloc] init];
     output.number = self.result;
-    NSDictionary* outputDictionary = [output toMap];
-    callback([_codec encode:outputDictionary]);
+    callback([_codec encode:output]);
   }
 }
 
-- (FlutterBinaryMessengerConnection)setMessageHandlerOnChannel:(nonnull NSString*)channel
+- (FlutterBinaryMessengerConnection)setMessageHandlerOnChannel:(nonnull NSString *)channel
                                           binaryMessageHandler:
                                               (FlutterBinaryMessageHandler _Nullable)handler {
   _handlers[channel] = [handler copy];
@@ -59,17 +59,17 @@ - (FlutterBinaryMessengerConnection)setMessageHandlerOnChannel:(nonnull NSString
 
 ///////////////////////////////////////////////////////////////////////////////////////////
 @interface MockApi2Host : NSObject<Api2Host>
-@property(nonatomic, copy) NSNumber* output;
-@property(nonatomic, retain) FlutterError* voidVoidError;
+@property(nonatomic, copy) NSNumber *output;
+@property(nonatomic, retain) FlutterError *voidVoidError;
 @end
 
 ///////////////////////////////////////////////////////////////////////////////////////////
 @implementation MockApi2Host
 
-- (void)calculate:(Value* _Nullable)input
-       completion:(nonnull void (^)(Value* _Nullable, FlutterError* _Nullable))completion {
+- (void)calculate:(Value *_Nullable)input
+       completion:(nonnull void (^)(Value *_Nullable, FlutterError *_Nullable))completion {
   if (self.output) {
-    Value* output = [[Value alloc] init];
+    Value *output = [[Value alloc] init];
     output.number = self.output;
     completion(output, nil);
   } else {
@@ -77,7 +77,7 @@ - (void)calculate:(Value* _Nullable)input
   }
 }
 
-- (void)voidVoid:(nonnull void (^)(FlutterError* _Nullable))completion {
+- (void)voidVoid:(nonnull void (^)(FlutterError *_Nullable))completion {
   completion(self.voidVoidError);
 }
 
@@ -91,14 +91,15 @@ @interface AsyncHandlersTest : XCTestCase
 @implementation AsyncHandlersTest
 
 - (void)testAsyncHost2Flutter {
-  MockBinaryMessenger* binaryMessenger = [[MockBinaryMessenger alloc] init];
+  MockBinaryMessenger *binaryMessenger =
+      [[MockBinaryMessenger alloc] initWithCodec:Api2FlutterGetCodec()];
   binaryMessenger.result = @(2);
-  Api2Flutter* api2Flutter = [[Api2Flutter alloc] initWithBinaryMessenger:binaryMessenger];
-  Value* input = [[Value alloc] init];
+  Api2Flutter *api2Flutter = [[Api2Flutter alloc] initWithBinaryMessenger:binaryMessenger];
+  Value *input = [[Value alloc] init];
   input.number = @(1);
-  XCTestExpectation* expectation = [self expectationWithDescription:@"calculate callback"];
+  XCTestExpectation *expectation = [self expectationWithDescription:@"calculate callback"];
   [api2Flutter calculate:input
-              completion:^(Value* _Nonnull output, NSError* _Nullable error) {
+              completion:^(Value *_Nonnull output, NSError *_Nullable error) {
                 XCTAssertEqual(output.number.intValue, 2);
                 [expectation fulfill];
               }];
@@ -106,16 +107,17 @@ - (void)testAsyncHost2Flutter {
 }
 
 - (void)testAsyncFlutter2HostVoidVoid {
-  MockBinaryMessenger* binaryMessenger = [[MockBinaryMessenger alloc] init];
-  MockApi2Host* mockApi2Host = [[MockApi2Host alloc] init];
+  MockBinaryMessenger *binaryMessenger =
+      [[MockBinaryMessenger alloc] initWithCodec:Api2HostGetCodec()];
+  MockApi2Host *mockApi2Host = [[MockApi2Host alloc] init];
   mockApi2Host.output = @(2);
   Api2HostSetup(binaryMessenger, mockApi2Host);
-  NSString* channelName = @"dev.flutter.pigeon.Api2Host.voidVoid";
+  NSString *channelName = @"dev.flutter.pigeon.Api2Host.voidVoid";
   XCTAssertNotNil(binaryMessenger.handlers[channelName]);
 
-  XCTestExpectation* expectation = [self expectationWithDescription:@"voidvoid callback"];
-  binaryMessenger.handlers[channelName](nil, ^(NSData* data) {
-    NSDictionary* outputMap = [binaryMessenger.codec decode:data];
+  XCTestExpectation *expectation = [self expectationWithDescription:@"voidvoid callback"];
+  binaryMessenger.handlers[channelName](nil, ^(NSData *data) {
+    NSDictionary *outputMap = [binaryMessenger.codec decode:data];
     XCTAssertEqualObjects(outputMap[@"result"], [NSNull null]);
     XCTAssertEqualObjects(outputMap[@"error"], [NSNull null]);
     [expectation fulfill];
@@ -124,16 +126,17 @@ - (void)testAsyncFlutter2HostVoidVoid {
 }
 
 - (void)testAsyncFlutter2HostVoidVoidError {
-  MockBinaryMessenger* binaryMessenger = [[MockBinaryMessenger alloc] init];
-  MockApi2Host* mockApi2Host = [[MockApi2Host alloc] init];
+  MockBinaryMessenger *binaryMessenger =
+      [[MockBinaryMessenger alloc] initWithCodec:Api2HostGetCodec()];
+  MockApi2Host *mockApi2Host = [[MockApi2Host alloc] init];
   mockApi2Host.voidVoidError = [FlutterError errorWithCode:@"code" message:@"message" details:nil];
   Api2HostSetup(binaryMessenger, mockApi2Host);
-  NSString* channelName = @"dev.flutter.pigeon.Api2Host.voidVoid";
+  NSString *channelName = @"dev.flutter.pigeon.Api2Host.voidVoid";
   XCTAssertNotNil(binaryMessenger.handlers[channelName]);
 
-  XCTestExpectation* expectation = [self expectationWithDescription:@"voidvoid callback"];
-  binaryMessenger.handlers[channelName](nil, ^(NSData* data) {
-    NSDictionary* outputMap = [binaryMessenger.codec decode:data];
+  XCTestExpectation *expectation = [self expectationWithDescription:@"voidvoid callback"];
+  binaryMessenger.handlers[channelName](nil, ^(NSData *data) {
+    NSDictionary *outputMap = [binaryMessenger.codec decode:data];
     XCTAssertNotNil(outputMap[@"error"]);
     XCTAssertEqualObjects(outputMap[@"error"][@"code"], mockApi2Host.voidVoidError.code);
     [expectation fulfill];
@@ -142,20 +145,21 @@ - (void)testAsyncFlutter2HostVoidVoidError {
 }
 
 - (void)testAsyncFlutter2Host {
-  MockBinaryMessenger* binaryMessenger = [[MockBinaryMessenger alloc] init];
-  MockApi2Host* mockApi2Host = [[MockApi2Host alloc] init];
+  MockBinaryMessenger *binaryMessenger =
+      [[MockBinaryMessenger alloc] initWithCodec:Api2HostGetCodec()];
+  MockApi2Host *mockApi2Host = [[MockApi2Host alloc] init];
   mockApi2Host.output = @(2);
   Api2HostSetup(binaryMessenger, mockApi2Host);
-  NSString* channelName = @"dev.flutter.pigeon.Api2Host.calculate";
+  NSString *channelName = @"dev.flutter.pigeon.Api2Host.calculate";
   XCTAssertNotNil(binaryMessenger.handlers[channelName]);
 
-  Value* input = [[Value alloc] init];
+  Value *input = [[Value alloc] init];
   input.number = @(1);
-  NSData* inputEncoded = [binaryMessenger.codec encode:[input toMap]];
-  XCTestExpectation* expectation = [self expectationWithDescription:@"calculate callback"];
-  binaryMessenger.handlers[channelName](inputEncoded, ^(NSData* data) {
-    NSDictionary* outputMap = [binaryMessenger.codec decode:data];
-    Value* output = [Value fromMap:outputMap[@"result"]];
+  NSData *inputEncoded = [binaryMessenger.codec encode:input];
+  XCTestExpectation *expectation = [self expectationWithDescription:@"calculate callback"];
+  binaryMessenger.handlers[channelName](inputEncoded, ^(NSData *data) {
+    NSDictionary *outputMap = [binaryMessenger.codec decode:data];
+    Value *output = outputMap[@"result"];
     XCTAssertEqual(output.number.intValue, 2);
     [expectation fulfill];
   });
@@ -163,18 +167,19 @@ - (void)testAsyncFlutter2Host {
 }
 
 - (void)testAsyncFlutter2HostError {
-  MockBinaryMessenger* binaryMessenger = [[MockBinaryMessenger alloc] init];
-  MockApi2Host* mockApi2Host = [[MockApi2Host alloc] init];
+  MockBinaryMessenger *binaryMessenger =
+      [[MockBinaryMessenger alloc] initWithCodec:Api2HostGetCodec()];
+  MockApi2Host *mockApi2Host = [[MockApi2Host alloc] init];
   Api2HostSetup(binaryMessenger, mockApi2Host);
-  NSString* channelName = @"dev.flutter.pigeon.Api2Host.calculate";
+  NSString *channelName = @"dev.flutter.pigeon.Api2Host.calculate";
   XCTAssertNotNil(binaryMessenger.handlers[channelName]);
 
-  Value* input = [[Value alloc] init];
+  Value *input = [[Value alloc] init];
   input.number = @(1);
-  NSData* inputEncoded = [binaryMessenger.codec encode:[input toMap]];
-  XCTestExpectation* expectation = [self expectationWithDescription:@"calculate callback"];
-  binaryMessenger.handlers[channelName](inputEncoded, ^(NSData* data) {
-    NSDictionary* outputMap = [binaryMessenger.codec decode:data];
+  NSData *inputEncoded = [binaryMessenger.codec encode:[input toMap]];
+  XCTestExpectation *expectation = [self expectationWithDescription:@"calculate callback"];
+  binaryMessenger.handlers[channelName](inputEncoded, ^(NSData *data) {
+    NSDictionary *outputMap = [binaryMessenger.codec decode:data];
     XCTAssertNotNil(outputMap[@"error"]);
     [expectation fulfill];
   });
diff --git a/packages/pigeon/platform_tests/ios_unit_tests/ios/RunnerTests/PrimitiveTest.m b/packages/pigeon/platform_tests/ios_unit_tests/ios/RunnerTests/PrimitiveTest.m
new file mode 100644
index 000000000000..26fb77c10aa7
--- /dev/null
+++ b/packages/pigeon/platform_tests/ios_unit_tests/ios/RunnerTests/PrimitiveTest.m
@@ -0,0 +1,94 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import <Flutter/Flutter.h>
+#import <XCTest/XCTest.h>
+#import "EchoMessenger.h"
+#import "primitive.gen.h"
+
+///////////////////////////////////////////////////////////////////////////////////////////
+@interface PrimitiveTest : XCTestCase
+@end
+
+///////////////////////////////////////////////////////////////////////////////////////////
+@implementation PrimitiveTest
+
+- (void)testIntPrimitive {
+  EchoBinaryMessenger* binaryMessenger = [[EchoBinaryMessenger alloc] init];
+  PrimitiveFlutterApi* api = [[PrimitiveFlutterApi alloc] initWithBinaryMessenger:binaryMessenger];
+  XCTestExpectation* expectation = [self expectationWithDescription:@"callback"];
+  [api anInt:@1
+      completion:^(NSNumber* _Nonnull result, NSError* _Nullable err) {
+        XCTAssertEqualObjects(@1, result);
+        [expectation fulfill];
+      }];
+  [self waitForExpectations:@[ expectation ] timeout:1.0];
+}
+
+- (void)testBoolPrimitive {
+  EchoBinaryMessenger* binaryMessenger = [[EchoBinaryMessenger alloc] init];
+  PrimitiveFlutterApi* api = [[PrimitiveFlutterApi alloc] initWithBinaryMessenger:binaryMessenger];
+  XCTestExpectation* expectation = [self expectationWithDescription:@"callback"];
+  NSNumber* arg = @YES;
+  [api aBool:arg
+      completion:^(NSNumber* _Nonnull result, NSError* _Nullable err) {
+        XCTAssertEqualObjects(arg, result);
+        [expectation fulfill];
+      }];
+  [self waitForExpectations:@[ expectation ] timeout:1.0];
+}
+
+- (void)testDoublePrimitive {
+  EchoBinaryMessenger* binaryMessenger = [[EchoBinaryMessenger alloc] init];
+  PrimitiveFlutterApi* api = [[PrimitiveFlutterApi alloc] initWithBinaryMessenger:binaryMessenger];
+  XCTestExpectation* expectation = [self expectationWithDescription:@"callback"];
+  NSNumber* arg = @(1.5);
+  [api aBool:arg
+      completion:^(NSNumber* _Nonnull result, NSError* _Nullable err) {
+        XCTAssertEqualObjects(arg, result);
+        [expectation fulfill];
+      }];
+  [self waitForExpectations:@[ expectation ] timeout:1.0];
+}
+
+- (void)testStringPrimitive {
+  EchoBinaryMessenger* binaryMessenger = [[EchoBinaryMessenger alloc] init];
+  PrimitiveFlutterApi* api = [[PrimitiveFlutterApi alloc] initWithBinaryMessenger:binaryMessenger];
+  XCTestExpectation* expectation = [self expectationWithDescription:@"callback"];
+  NSString* arg = @"hello";
+  [api aString:arg
+      completion:^(NSString* _Nonnull result, NSError* _Nullable err) {
+        XCTAssertEqualObjects(arg, result);
+        [expectation fulfill];
+      }];
+  [self waitForExpectations:@[ expectation ] timeout:1.0];
+}
+
+- (void)testListPrimitive {
+  EchoBinaryMessenger* binaryMessenger = [[EchoBinaryMessenger alloc] init];
+  PrimitiveFlutterApi* api = [[PrimitiveFlutterApi alloc] initWithBinaryMessenger:binaryMessenger];
+  XCTestExpectation* expectation = [self expectationWithDescription:@"callback"];
+  NSArray* arg = @[ @"hello" ];
+  [api aList:arg
+      completion:^(NSArray* _Nonnull result, NSError* _Nullable err) {
+        XCTAssertEqualObjects(arg, result);
+        [expectation fulfill];
+      }];
+  [self waitForExpectations:@[ expectation ] timeout:1.0];
+}
+
+- (void)testMapPrimitive {
+  EchoBinaryMessenger* binaryMessenger = [[EchoBinaryMessenger alloc] init];
+  PrimitiveFlutterApi* api = [[PrimitiveFlutterApi alloc] initWithBinaryMessenger:binaryMessenger];
+  XCTestExpectation* expectation = [self expectationWithDescription:@"callback"];
+  NSDictionary* arg = @{ @"hello" : @1 };
+  [api aMap:arg
+      completion:^(NSDictionary* _Nonnull result, NSError* _Nullable err) {
+        XCTAssertEqualObjects(arg, result);
+        [expectation fulfill];
+      }];
+  [self waitForExpectations:@[ expectation ] timeout:1.0];
+}
+
+@end
diff --git a/packages/pigeon/run_tests.sh b/packages/pigeon/run_tests.sh
index af121e4b8d7b..341967574189 100755
--- a/packages/pigeon/run_tests.sh
+++ b/packages/pigeon/run_tests.sh
@@ -249,6 +249,7 @@ run_ios_unittests() {
   gen_ios_unittests_code ./pigeons/host2flutter.dart ""
   gen_ios_unittests_code ./pigeons/list.dart "LST"
   gen_ios_unittests_code ./pigeons/message.dart ""
+  gen_ios_unittests_code ./pigeons/primitive.dart ""
   gen_ios_unittests_code ./pigeons/void_arg_flutter.dart "VAF"
   gen_ios_unittests_code ./pigeons/void_arg_host.dart "VAH"
   gen_ios_unittests_code ./pigeons/voidflutter.dart "VF"
@@ -302,6 +303,7 @@ run_android_unittests() {
   gen_android_unittests_code ./pigeons/java_double_host_api.dart JavaDoubleHostApi
   gen_android_unittests_code ./pigeons/list.dart PigeonList
   gen_android_unittests_code ./pigeons/message.dart MessagePigeon
+  gen_android_unittests_code ./pigeons/primitive.dart Primitive
   gen_android_unittests_code ./pigeons/void_arg_flutter.dart VoidArgFlutter
   gen_android_unittests_code ./pigeons/void_arg_host.dart VoidArgHost
   gen_android_unittests_code ./pigeons/voidflutter.dart VoidFlutter
diff --git a/packages/pigeon/test/dart_generator_test.dart b/packages/pigeon/test/dart_generator_test.dart
index c26e85d13dc0..04b3488b303d 100644
--- a/packages/pigeon/test/dart_generator_test.dart
+++ b/packages/pigeon/test/dart_generator_test.dart
@@ -392,7 +392,7 @@ void main() {
     expect(mainCode, contains('class Api {'));
     expect(mainCode, isNot(contains('abstract class ApiMock')));
     expect(mainCode, isNot(contains('.ApiMock.doSomething')));
-    expect(mainCode, isNot(contains('\'${Keys.result}\': output.encode()')));
+    expect(mainCode, isNot(contains('\'${Keys.result}\': output')));
     expect(mainCode, isNot(contains('return <Object, Object>{};')));
     generateTestDart(
         const DartOptions(isNullSafe: false), root, testCodeSink, "fo'o.dart");
@@ -401,7 +401,7 @@ void main() {
     expect(testCode, isNot(contains('class Api {')));
     expect(testCode, contains('abstract class ApiMock'));
     expect(testCode, isNot(contains('.ApiMock.doSomething')));
-    expect(testCode, contains('\'${Keys.result}\': output.encode()'));
+    expect(testCode, contains('\'${Keys.result}\': output'));
     expect(testCode, contains('return <Object, Object>{};'));
   });
 
diff --git a/packages/pigeon/test/java_generator_test.dart b/packages/pigeon/test/java_generator_test.dart
index 84276b0490d2..4ac1ab63071b 100644
--- a/packages/pigeon/test/java_generator_test.dart
+++ b/packages/pigeon/test/java_generator_test.dart
@@ -357,7 +357,7 @@ void main() {
     expect(
         code,
         contains(
-            'api.doSomething(input, result -> { wrapped.put("result", result.toMap()); reply.reply(wrapped); });'));
+            'api.doSomething(input, result -> { wrapped.put("result", result); reply.reply(wrapped); });'));
     expect(code, contains('channel.setMessageHandler(null)'));
   });
 
diff --git a/packages/pigeon/test/objc_generator_test.dart b/packages/pigeon/test/objc_generator_test.dart
index 383e84ebd673..8acf43920cc9 100644
--- a/packages/pigeon/test/objc_generator_test.dart
+++ b/packages/pigeon/test/objc_generator_test.dart
@@ -409,7 +409,7 @@ void main() {
     generateObjcSource(const ObjcOptions(prefix: 'ABC'), root, sink);
     final String code = sink.toString();
     expect(code, contains('ABCInput fromMap'));
-    expect(code, matches('ABCInput.*=.*ABCInput fromMap'));
+    expect(code, matches('ABCInput.*=.*message'));
     expect(code, contains('void ABCApiSetup('));
   });
 
diff --git a/packages/pigeon/test/pigeon_lib_test.dart b/packages/pigeon/test/pigeon_lib_test.dart
index c716b8a0b0f7..6aba0a002f30 100644
--- a/packages/pigeon/test/pigeon_lib_test.dart
+++ b/packages/pigeon/test/pigeon_lib_test.dart
@@ -307,28 +307,6 @@ abstract class NestorApi {
     expect(classNames.contains('OnlyVisibleFromNesting'), true);
   });
 
-  test('invalid datatype for argument', () {
-    const String code = '''
-@HostApi()
-abstract class InvalidArgTypeApi {
-  void doit(bool value);
-}
-''';
-    final ParseResults results = _parseSource(code);
-    expect(results.errors.length, 1);
-  });
-
-  test('invalid datatype for argument', () {
-    const String code = '''
-@HostApi()
-abstract class InvalidReturnTypeApi {
-  bool doit();
-}
-''';
-    final ParseResults results = _parseSource(code);
-    expect(results.errors.length, 1);
-  });
-
   test('null safety flag', () {
     final PigeonOptions results =
         Pigeon.parseArgs(<String>['--dart_null_safety']);
@@ -546,32 +524,6 @@ abstract class Api {
     expect(results.errors[0].message, contains('Nullable'));
   });
 
-  test('primitive arguments', () {
-    const String code = '''
-@HostApi()
-abstract class Api {
-  void doit(int foo);
-}
-''';
-    final ParseResults results = _parseSource(code);
-    expect(results.errors.length, 1);
-    expect(results.errors[0].lineNumber, 3);
-    expect(results.errors[0].message, contains('Primitive'));
-  });
-
-  test('primitive return', () {
-    const String code = '''
-@HostApi()
-abstract class Api {
-  int doit();
-}
-''';
-    final ParseResults results = _parseSource(code);
-    expect(results.errors.length, 1);
-    expect(results.errors[0].lineNumber, 3);
-    expect(results.errors[0].message, contains('Primitive'));
-  });
-
   test('test invalid import', () {
     const String code = 'import \'foo.dart\';\n';
     final ParseResults results = _parseSource(code);