diff --git a/README.md b/README.md
index e64bb345..3f09dbd8 100644
--- a/README.md
+++ b/README.md
@@ -4,6 +4,12 @@ Redux DevTools
 A live-editing time travel environment for [Redux](https://github.com/rackt/redux).  
 **[See Dan's React Europe talk demoing it!](http://youtube.com/watch?v=xsSnOQynTHs)**
 
+[![build status](https://img.shields.io/travis/gaearon/redux-devtools/master.svg?style=flat-square)](https://travis-ci.org/gaearon/redux-devtools)
+[![npm version](https://img.shields.io/npm/v/redux-devtools.svg?style=flat-square)](https://www.npmjs.com/package/redux-devtools)
+[![npm downloads](https://img.shields.io/npm/dm/redux-devtools.svg?style=flat-square)](https://www.npmjs.com/package/redux-devtools)
+[![redux channel on slack](https://img.shields.io/badge/slack-redux@reactiflux-61DAFB.svg?style=flat-square)](http://www.reactiflux.com)
+
+
 ![](http://i.imgur.com/J4GeW0M.gif)
 
 ### Features
diff --git a/src/persistState.js b/src/persistState.js
index 976a3b05..c12e49ce 100644
--- a/src/persistState.js
+++ b/src/persistState.js
@@ -65,7 +65,7 @@ export default function persistState(sessionId, stateDeserializer = null, action
         try {
           localStorage.setItem(key, JSON.stringify(store.getState()));
         } catch (e) {
-          console.warn('Could not write debug session from localStorage:', e);
+          console.warn('Could not write debug session to localStorage:', e);
         }
 
         return action;
diff --git a/test/devTools.spec.js b/test/devTools.spec.js
index 234ef10f..672fb8b9 100644
--- a/test/devTools.spec.js
+++ b/test/devTools.spec.js
@@ -14,6 +14,7 @@ function counterWithBug(state = 0, action) {
   switch (action.type) {
     case 'INCREMENT': return state + 1;
     case 'DECREMENT': return mistake - 1; // eslint-disable-line no-undef
+    case 'SET_UNDEFINED': return undefined;
     default: return state;
   }
 }
@@ -99,7 +100,7 @@ describe('devTools', () => {
     expect(store.getState()).toBe(1);
   });
 
-  it('sweep disabled actions', () => {
+  it('should sweep disabled actions', () => {
     // stateIndex 0 = @@INIT
     store.dispatch({ type: 'INCREMENT' });
     store.dispatch({ type: 'DECREMENT' });
@@ -153,13 +154,14 @@ describe('devTools', () => {
     store.dispatch({ type: 'INCREMENT' });
     expect(store.getState()).toBe(1);
 
-    let devStoreState = store.devToolsStore.getState();
-    devStoreState.committedState = 10;
-    devStoreState.stagedActions[2] = { type: 'INCREMENT' };
+    let stagedActions = [...store.devToolsStore.getState().stagedActions];
+    // replace DECREMENT with INCREMENT (stagedAction[0] is @@INIT)
+    stagedActions[2] = { type: 'INCREMENT' };
+    const committedState = 10;
 
     devToolsStore.dispatch(ActionCreators.recomputeStates(
-      devStoreState.committedState,
-      devStoreState.stagedActions
+      committedState,
+      stagedActions
     ));
 
     expect(store.getState()).toBe(13);
@@ -201,18 +203,13 @@ describe('devTools', () => {
     spy.restore();
   });
 
-  it('returns the last non-undefined state from getState', () => {
-    let spy = spyOn(console, 'error');
+  it('should return the last non-undefined state from getState', () => {
+    let storeWithBug = devTools()(createStore)(counterWithBug);
+    storeWithBug.dispatch({ type: 'INCREMENT' });
+    storeWithBug.dispatch({ type: 'INCREMENT' });
+    expect(storeWithBug.getState()).toBe(2);
 
-    store.dispatch({ type: 'INCREMENT' });
-    store.dispatch({ type: 'DECREMENT' });
-    store.dispatch({ type: 'INCREMENT' });
-    store.dispatch({ type: 'INCREMENT' });
-    expect(store.getState()).toBe(2);
-
-    store.replaceReducer(counterWithBug);
-    expect(store.getState()).toBe(1);
-
-    spy.restore();
+    storeWithBug.dispatch({ type: 'SET_UNDEFINED' });
+    expect(storeWithBug.getState()).toBe(2);
   });
 });
diff --git a/test/persistState.spec.js b/test/persistState.spec.js
new file mode 100644
index 00000000..4cafe1c5
--- /dev/null
+++ b/test/persistState.spec.js
@@ -0,0 +1,123 @@
+import expect from 'expect';
+import devTools from '../src/devTools';
+import persistState from '../src/persistState';
+import { compose, createStore } from 'redux';
+
+describe('persistState', () => {
+  let savedLocalStorage = global.localStorage;
+
+  beforeEach(() => {
+    global.localStorage = {
+      store: {},
+      getItem(key) {
+        return this.store[key] || null;
+      },
+      setItem(key, value) {
+        this.store[key] = value;
+      },
+      removeItem(key) {
+        delete this.store[key];
+      },
+      clear() {
+        this.store = {};
+      }
+    };
+  });
+
+  after(() => {
+    global.localStorage = savedLocalStorage;
+  });
+
+  const reducer = (state = 0, action) => {
+    switch (action.type) {
+    case 'INCREMENT':
+      return state + 1;
+    case 'DECREMENT':
+      return state - 1;
+    default:
+      return state;
+    }
+  };
+
+  it('should persist state', () => {
+    const finalCreateStore = compose(devTools(), persistState('id'))(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(2);
+  });
+
+  it('should not persist state if no session id', () => {
+    const finalCreateStore = compose(devTools(), persistState())(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(0);
+  });
+
+  it('should run with a custom state deserializer', () => {
+    const oneLess = state => state === undefined ? -1 : state - 1;
+    const finalCreateStore = compose(devTools(), persistState('id', oneLess))(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(1);
+  });
+
+  it('should run with a custom action deserializer', () => {
+    const incToDec = action => action.type === 'INCREMENT' ? { type: 'DECREMENT' } : action;
+    const finalCreateStore = compose(devTools(), persistState('id', null, incToDec))(createStore);
+    const store = finalCreateStore(reducer);
+    expect(store.getState()).toBe(0);
+
+    store.dispatch({ type: 'INCREMENT' });
+    store.dispatch({ type: 'INCREMENT' });
+    expect(store.getState()).toBe(2);
+
+    const store2 = finalCreateStore(reducer);
+    expect(store2.getState()).toBe(-2);
+  });
+
+  it('should warn if read from localStorage fails', () => {
+    const spy = expect.spyOn(console, 'warn');
+    const finalCreateStore = compose(devTools(), persistState('id'))(createStore);
+    delete global.localStorage.getItem;
+    finalCreateStore(reducer);
+
+    expect(spy.calls).toContain(
+      /Could not read debug session from localStorage/,
+      (call, errMsg) => call.arguments[0].match(errMsg)
+    );
+
+    spy.restore();
+  });
+  it('should warn if write to localStorage fails', () => {
+    const spy = expect.spyOn(console, 'warn');
+    const finalCreateStore = compose(devTools(), persistState('id'))(createStore);
+    delete global.localStorage.setItem;
+    const store = finalCreateStore(reducer);
+
+    store.dispatch({ type: 'INCREMENT' });
+    expect(spy.calls).toContain(
+      /Could not write debug session to localStorage/,
+      (call, errMsg) => call.arguments[0].match(errMsg)
+    );
+
+    spy.restore();
+  });
+});