diff --git a/index.js b/index.js
index 8c79279..b951fd9 100644
--- a/index.js
+++ b/index.js
@@ -425,6 +425,7 @@ var extensions = {
       },
     },
   ],
+  '.cts': ['ts-node/register'],
   '.tsx': [
     'ts-node/register',
     'sucrase/register/tsx',
diff --git a/test/fixtures/cts/0/package.json b/test/fixtures/cts/0/package.json
new file mode 100644
index 0000000..e11b5ba
--- /dev/null
+++ b/test/fixtures/cts/0/package.json
@@ -0,0 +1,6 @@
+{
+  "dependencies": {
+    "ts-node": "^10.8.0",
+    "typescript": "^4.7.4"
+  }
+}
diff --git a/test/fixtures/cts/0/test.cts b/test/fixtures/cts/0/test.cts
new file mode 100644
index 0000000..3fa0969
--- /dev/null
+++ b/test/fixtures/cts/0/test.cts
@@ -0,0 +1,19 @@
+var test: {
+  data: {
+    trueKey: boolean;
+    falseKey: boolean;
+    subKey: {
+      subProp: number;
+    };
+  };
+} = {
+  data: {
+    trueKey: true,
+    falseKey: false,
+    subKey: {
+      subProp: 1,
+    },
+  },
+};
+
+export default test;
diff --git a/test/fixtures/cts/0/tsconfig.json b/test/fixtures/cts/0/tsconfig.json
new file mode 100644
index 0000000..ca687b6
--- /dev/null
+++ b/test/fixtures/cts/0/tsconfig.json
@@ -0,0 +1,11 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+    "module": "commonjs",
+    "declaration": false,
+    "noImplicitAny": false,
+    "removeComments": true,
+    "sourceMap": true,
+    "outDir": ".tmp"
+  }
+}
diff --git a/test/fixtures/ts/0/package.json b/test/fixtures/ts/0/package.json
index 5240475..e11b5ba 100644
--- a/test/fixtures/ts/0/package.json
+++ b/test/fixtures/ts/0/package.json
@@ -1,6 +1,6 @@
 {
   "dependencies": {
-    "ts-node": "^7.0.1",
-    "typescript": "^3.2.2"
+    "ts-node": "^10.8.0",
+    "typescript": "^4.7.4"
   }
 }
diff --git a/test/fixtures/tsx/0/package.json b/test/fixtures/tsx/0/package.json
index 5240475..b5ae145 100644
--- a/test/fixtures/tsx/0/package.json
+++ b/test/fixtures/tsx/0/package.json
@@ -1,6 +1,6 @@
 {
   "dependencies": {
-    "ts-node": "^7.0.1",
-    "typescript": "^3.2.2"
+    "ts-node": "^10.8.0",
+    "typescript": "4.7.4"
   }
 }
diff --git a/test/index.js b/test/index.js
index 295a860..1f9ca83 100644
--- a/test/index.js
+++ b/test/index.js
@@ -154,6 +154,7 @@ describe('interpret.extensions', function () {
 
         switch (extension) {
           case '.ts':
+          case '.cts':
           case '.tsx':
           case '.esm.js':
           case '.babel.tsx':