diff --git a/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/test_toolkit_v1.x.x.js b/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/test_toolkit_v1.x.x.js
index e1f62e2750..8635bf11f8 100644
--- a/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/test_toolkit_v1.x.x.js
+++ b/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/test_toolkit_v1.x.x.js
@@ -5,6 +5,8 @@ import {
   createReducer,
   configureStore,
   type Middleware,
+  type Store,
+  type Action,
 } from '@reduxjs/toolkit';
 
 describe('@redux/toolkit', () => {
@@ -63,6 +65,41 @@ describe('@redux/toolkit', () => {
       configureStore({
         reducer,
       });
+
+      const store: Store<{
+        test: { ... },
+        test2: number,
+        ...
+      }, Action<{ ... }>> = configureStore({
+        reducer: {
+          test: (a) => ({}),
+          test2: (a) => 2,
+        },
+      });
+
+      const failedStore: Store<{|
+        test: { ... },
+        test2: number,
+      // $FlowExpectedError[prop-missing] foo is missing
+      |}, Action<{ ... }>> = configureStore({
+        reducer: {
+          test: (a) => ({}),
+          test2: (a) => 2,
+          foo: () => 'bar',
+        },
+      });
+
+      // const failedStore2: Store<{
+      //   test: { ... },
+      //   // Expect this to fail but currently does not
+      //   test2: string,
+      //   ...
+      // }, Action<{ ... }>> = configureStore({
+      //   reducer: {
+      //     test: (a) => ({}),
+      //     test2: (a) => 2,
+      //   },
+      // });
     });
 
     test('full example', () => {
diff --git a/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/toolkit_v1.x.x.js b/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/toolkit_v1.x.x.js
index b3748382a9..c7b4794196 100644
--- a/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/toolkit_v1.x.x.js
+++ b/definitions/npm/@reduxjs/toolkit_v1.x.x/flow_v0.104.x-/toolkit_v1.x.x.js
@@ -49,7 +49,7 @@ declare module '@reduxjs/toolkit' {
 
   // --------------------
 
-  declare type Middlewares<S> = $ReadOnlyArray<Middleware<{ ... }, S>>;
+  declare type Middlewares<S> = $ReadOnlyArray<Middleware<S, { type: any, ... }>>;
 
   declare type DevToolsOptions = {|
     /**
@@ -423,6 +423,8 @@ declare module '@reduxjs/toolkit' {
    */
   declare type ConfigureEnhancersCallback = <S, A>(defaultEnhancers: $ReadOnlyArray<StoreEnhancer<S, A>>) => Array<StoreEnhancer<S, A>>;
 
+  declare type ReducersMapObject = <V>(V) => Reducer<V, Action<any>>;
+
   /**
    * Options for `configureStore()`.
    */
@@ -431,10 +433,7 @@ declare module '@reduxjs/toolkit' {
      * A single reducer function that will be used as the root reducer, or an
      * object of slice reducers that will be passed to `combineReducers()`.
      */
-    reducer: Reducer<S, A> | {
-      [key: string]: Reducer<S, A>,
-      ...
-    },
+    reducer: Reducer<S, A> | $ObjMap<S, ReducersMapObject>,
     /**
      * An array of Redux middleware to install. If not supplied, defaults to
      * the set of middleware returned by `getDefaultMiddleware()`.