--- a/dom/media/webspeech/synth/nsSpeechTask.cpp
+++ b/dom/media/webspeech/synth/nsSpeechTask.cpp
@@ -742,16 +742,20 @@ nsSpeechTask::WindowVolumeChanged(float 
 {
   SetAudioOutputVolume(aMuted ? 0.0 : mVolume * aVolume);
   return NS_OK;
 }
 
 NS_IMETHODIMP
 nsSpeechTask::WindowSuspendChanged(nsSuspendedTypes aSuspend)
 {
+  if (!mUtterance) {
+    return NS_OK;
+  }
+
   if (aSuspend == nsISuspendedTypes::NONE_SUSPENDED &&
       mUtterance->mPaused) {
     Resume();
   } else if (aSuspend != nsISuspendedTypes::NONE_SUSPENDED &&
              !mUtterance->mPaused) {
     Pause();
   }
   return NS_OK;