diff --git a/packages/quicktype-core/src/language/Java/JavaJacksonRenderer.ts b/packages/quicktype-core/src/language/Java/JavaJacksonRenderer.ts
index 15c24bebed..35407b4cb7 100644
--- a/packages/quicktype-core/src/language/Java/JavaJacksonRenderer.ts
+++ b/packages/quicktype-core/src/language/Java/JavaJacksonRenderer.ts
@@ -10,7 +10,10 @@ import {
     type TypeKind,
     UnionType,
 } from "../../Type/index.js";
-import { removeNullFromUnion } from "../../Type/TypeUtils.js";
+import {
+    nullableFromUnion,
+    removeNullFromUnion,
+} from "../../Type/TypeUtils.js";
 
 import { JavaRenderer } from "./JavaRenderer.js";
 import { stringEscape } from "./utils.js";
@@ -58,7 +61,12 @@ export class JacksonRenderer extends JavaRenderer {
             `@JsonProperty("${stringEscape(jsonName)}")`,
         ];
 
-        switch (p.type.kind) {
+        const propertyType =
+            p.type instanceof UnionType
+                ? (nullableFromUnion(p.type) ?? p.type)
+                : p.type;
+
+        switch (propertyType.kind) {
             case "date-time":
                 this._dateTimeProvider.dateTimeJacksonAnnotations.forEach(
                     (annotation) => {
diff --git a/test/inputs/schema/optional-date-time.1.fail.date-time.json b/test/inputs/schema/optional-date-time.1.fail.date-time.json
new file mode 100644
index 0000000000..f7c14ea5ff
--- /dev/null
+++ b/test/inputs/schema/optional-date-time.1.fail.date-time.json
@@ -0,0 +1,8 @@
+{
+    "required-date": "2024-01-02",
+    "required-time": "12:34:56Z",
+    "required-date-time": "not a valid date-time at all",
+    "optional-date": "2024-01-02",
+    "optional-time": "12:34:56Z",
+    "optional-date-time": "2024-01-02T12:34:56Z"
+}
diff --git a/test/inputs/schema/optional-date-time.1.json b/test/inputs/schema/optional-date-time.1.json
new file mode 100644
index 0000000000..ba76d40946
--- /dev/null
+++ b/test/inputs/schema/optional-date-time.1.json
@@ -0,0 +1,8 @@
+{
+    "required-date": "2024-01-02",
+    "required-time": "12:34:56Z",
+    "required-date-time": "2024-01-02T12:34:56Z",
+    "optional-date": "2024-01-02",
+    "optional-time": "12:34:56Z",
+    "optional-date-time": "2024-01-02T12:34:56Z"
+}
diff --git a/test/inputs/schema/optional-date-time.schema b/test/inputs/schema/optional-date-time.schema
new file mode 100644
index 0000000000..485d7f1a02
--- /dev/null
+++ b/test/inputs/schema/optional-date-time.schema
@@ -0,0 +1,35 @@
+{
+    "type": "object",
+    "additionalProperties": false,
+    "properties": {
+        "required-date": {
+            "type": "string",
+            "format": "date"
+        },
+        "required-time": {
+            "type": "string",
+            "format": "time"
+        },
+        "required-date-time": {
+            "type": "string",
+            "format": "date-time"
+        },
+        "optional-date": {
+            "type": "string",
+            "format": "date"
+        },
+        "optional-time": {
+            "type": "string",
+            "format": "time"
+        },
+        "optional-date-time": {
+            "type": "string",
+            "format": "date-time"
+        }
+    },
+    "required": [
+        "required-date",
+        "required-time",
+        "required-date-time"
+    ]
+}