diff --git a/src/createDispatcher.js b/src/createDispatcher.js
index 9a928b8c94f..04780ecc3f1 100644
--- a/src/createDispatcher.js
+++ b/src/createDispatcher.js
@@ -1,15 +1,25 @@
+/* @flow */
+
 import compose from './utils/composeMiddleware';
 
-export default function createDispatcher(store, middlewares = []) {
-  return function dispatcher(initialState, setState) {
-    let state = setState(store(initialState, {}));
+import { Middleware, Store, Action, State, Dispatcher } from './types';
+
+export default function createDispatcher(
+  store: Store,
+  middlewares: (Middleware[] | (getState: () => State) => Middleware[]) = []
+): Dispatcher {
+  return function dispatcher(
+    initialState: State,
+    setState: (state: State) => State
+  ) {
+    var state: State = setState(store(initialState, {}));
 
-    function dispatch(action) {
+    function dispatch(action: Action): Action {
       state = setState(store(state, action));
       return action;
     }
 
-    function getState() {
+    function getState(): State {
       return state;
     }
 
@@ -17,6 +27,6 @@ export default function createDispatcher(store, middlewares = []) {
       middlewares = middlewares(getState);
     }
 
-    return compose(...middlewares, dispatch);
+    return compose(...(middlewares: Middleware[]), dispatch);
   };
 }
diff --git a/src/utils/composeStores.js b/src/utils/composeStores.js
index 9aa2442a802..78b49094d1b 100644
--- a/src/utils/composeStores.js
+++ b/src/utils/composeStores.js
@@ -1,9 +1,13 @@
+/* @flow */
+
 import mapValues from 'lodash/object/mapValues';
 
-export default function composeStores(stores) {
-  return function Composition(atom = {}, action) {
+import { Store, Action, State } from '../types';
+
+export default function composeStores(stores: Store[]): Store {
+  return function Composition(state: State = {}, action: Action) {
     return mapValues(stores, (store, key) =>
-      store(atom[key], action)
+      store(state[key], action)
     );
   };
 }