diff --git a/core/java/android/webkit/DeviceMotionService.java b/core/java/android/webkit/DeviceMotionService.java
index 7d7a0f05e36e4..b4d5759dcb9a7 100755
--- a/core/java/android/webkit/DeviceMotionService.java
+++ b/core/java/android/webkit/DeviceMotionService.java
@@ -99,6 +99,7 @@ final class DeviceMotionService implements SensorEventListener {
         mUpdateRunnable = new Runnable() {
             @Override
             public void run() {
+                assert mIsRunning;
                 mManager.onMotionChange(new Double(mLastAcceleration[0]),
                         new Double(mLastAcceleration[1]), new Double(mLastAcceleration[2]),
                         INTERVAL_MILLIS);
@@ -157,6 +158,11 @@ final class DeviceMotionService implements SensorEventListener {
         assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
         assert(event.sensor.getType() == Sensor.TYPE_ACCELEROMETER);
 
+        // We may get callbacks after the call to getSensorManager().unregisterListener() returns.
+        if (!mIsRunning) {
+            return;
+        }
+
         boolean firstData = mLastAcceleration == null;
         mLastAcceleration = event.values;
         if (firstData) {
diff --git a/core/java/android/webkit/DeviceOrientationService.java b/core/java/android/webkit/DeviceOrientationService.java
index f3c057627a22b..47c8ab79b9189 100755
--- a/core/java/android/webkit/DeviceOrientationService.java
+++ b/core/java/android/webkit/DeviceOrientationService.java
@@ -188,6 +188,7 @@ final class DeviceOrientationService implements SensorEventListener {
         assert(event.values.length == 3);
         assert WebViewCore.THREAD_NAME.equals(Thread.currentThread().getName());
 
+        // We may get callbacks after the call to getSensorManager().unregisterListener() returns.
         if (!mIsRunning) {
             return;
         }