diff --git a/packages/redux-devtools-app/jest.config.js b/packages/redux-devtools-app/jest.config.js
index a1f53444..7e5b0b28 100644
--- a/packages/redux-devtools-app/jest.config.js
+++ b/packages/redux-devtools-app/jest.config.js
@@ -3,6 +3,6 @@ module.exports = {
   setupFilesAfterEnv: ['<rootDir>/test/setup.ts'],
   testEnvironment: 'jsdom',
   moduleNameMapper: {
-    '\\.css$': '<rootDir>/test/__mocks__/styleMock.ts',
+    '\\.css$': '<rootDir>/test/__mocks__/styleMock.js',
   },
 };
diff --git a/packages/redux-devtools-app/test/__mocks__/styleMock.js b/packages/redux-devtools-app/test/__mocks__/styleMock.js
new file mode 100644
index 00000000..f053ebf7
--- /dev/null
+++ b/packages/redux-devtools-app/test/__mocks__/styleMock.js
@@ -0,0 +1 @@
+module.exports = {};
diff --git a/packages/redux-devtools-app/test/__mocks__/styleMock.ts b/packages/redux-devtools-app/test/__mocks__/styleMock.ts
deleted file mode 100644
index ff8b4c56..00000000
--- a/packages/redux-devtools-app/test/__mocks__/styleMock.ts
+++ /dev/null
@@ -1 +0,0 @@
-export default {};