diff --git a/flow/jest.js b/flow/jest.js
index a4b9275e5ea..5dd8790ce2b 100644
--- a/flow/jest.js
+++ b/flow/jest.js
@@ -810,7 +810,7 @@ type JestObjectType = {
    * Returns a new, unused mock function. Optionally takes a mock
    * implementation.
    */
-  fn<TArguments: $ReadOnlyArray<mixed> = $ReadOnlyArray<mixed>, TReturn = any>(
+  fn<TArguments: $ReadOnlyArray<mixed> = $ReadOnlyArray<any>, TReturn = any>(
     implementation?: (...args: TArguments) => TReturn,
   ): JestMockFn<TArguments, TReturn>,
   /**