diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
index 62aab9ca5c062..44904e0aae7ee 100644
--- a/src/compiler/checker.ts
+++ b/src/compiler/checker.ts
@@ -10519,7 +10519,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         // function/class/{} initializers are themselves containers, so they won't merge in the same way as other initializers
         const container = getAssignedExpandoInitializer(symbol.valueDeclaration);
         if (container) {
-            const tag = getJSDocTypeTag(container);
+            const tag = isInJSFile(container) ? getJSDocTypeTag(container) : undefined;
             if (tag && tag.typeExpression) {
                 return getTypeFromTypeNode(tag.typeExpression);
             }
diff --git a/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.js b/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.js
new file mode 100644
index 0000000000000..a9693850eec11
--- /dev/null
+++ b/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.js
@@ -0,0 +1,17 @@
+//// [expandoFunctionContextualTypesJSDocInTs.ts]
+export function Foo() { }
+
+// This comment should have no effect; this is a TS file.
+/** @type {never} */
+Foo.bar = () => { };
+
+
+//// [expandoFunctionContextualTypesJSDocInTs.js]
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.Foo = void 0;
+function Foo() { }
+exports.Foo = Foo;
+// This comment should have no effect; this is a TS file.
+/** @type {never} */
+Foo.bar = function () { };
diff --git a/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.symbols b/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.symbols
new file mode 100644
index 0000000000000..667bc1dd8c341
--- /dev/null
+++ b/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.symbols
@@ -0,0 +1,11 @@
+=== tests/cases/compiler/expandoFunctionContextualTypesJSDocInTs.ts ===
+export function Foo() { }
+>Foo : Symbol(Foo, Decl(expandoFunctionContextualTypesJSDocInTs.ts, 0, 0), Decl(expandoFunctionContextualTypesJSDocInTs.ts, 0, 25))
+
+// This comment should have no effect; this is a TS file.
+/** @type {never} */
+Foo.bar = () => { };
+>Foo.bar : Symbol(Foo.bar, Decl(expandoFunctionContextualTypesJSDocInTs.ts, 0, 25))
+>Foo : Symbol(Foo, Decl(expandoFunctionContextualTypesJSDocInTs.ts, 0, 0), Decl(expandoFunctionContextualTypesJSDocInTs.ts, 0, 25))
+>bar : Symbol(Foo.bar, Decl(expandoFunctionContextualTypesJSDocInTs.ts, 0, 25))
+
diff --git a/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.types b/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.types
new file mode 100644
index 0000000000000..7e818015f1a79
--- /dev/null
+++ b/tests/baselines/reference/expandoFunctionContextualTypesJSDocInTs.types
@@ -0,0 +1,13 @@
+=== tests/cases/compiler/expandoFunctionContextualTypesJSDocInTs.ts ===
+export function Foo() { }
+>Foo : typeof Foo
+
+// This comment should have no effect; this is a TS file.
+/** @type {never} */
+Foo.bar = () => { };
+>Foo.bar = () => { } : () => void
+>Foo.bar : () => void
+>Foo : typeof Foo
+>bar : () => void
+>() => { } : () => void
+
diff --git a/tests/cases/compiler/expandoFunctionContextualTypesJSDocInTs.ts b/tests/cases/compiler/expandoFunctionContextualTypesJSDocInTs.ts
new file mode 100644
index 0000000000000..c26397a764a80
--- /dev/null
+++ b/tests/cases/compiler/expandoFunctionContextualTypesJSDocInTs.ts
@@ -0,0 +1,5 @@
+export function Foo() { }
+
+// This comment should have no effect; this is a TS file.
+/** @type {never} */
+Foo.bar = () => { };