diff --git a/xpcom/threads/TimerThread.cpp b/xpcom/threads/TimerThread.cpp
index d0ef5130eb64..a740b5e852a8 100644
--- a/xpcom/threads/TimerThread.cpp
+++ b/xpcom/threads/TimerThread.cpp
@@ -46,7 +46,7 @@ NS_IMPL_THREADSAFE_ISUPPORTS1(TimerThread, nsIRunnable)
 TimerThread::TimerThread() :
   mLock(nsnull),
   mCondVar(nsnull),
-  mProcessing(PR_FALSE),
+  mShutdown(PR_FALSE),
   mWaiting(PR_FALSE),
   mDelayLineCounter(0),
   mMinTimerPeriod(0),
@@ -108,7 +108,7 @@ nsresult TimerThread::Shutdown()
   {   // lock scope
     nsAutoLock lock(mLock);
 
-    mProcessing = PR_FALSE;
+    mShutdown = PR_TRUE;
 
     // notify the cond var so that Run() can return
     if (mCondVar && mWaiting)
@@ -184,9 +184,8 @@ void TimerThread::UpdateFilter(PRUint32 aDelay, PRIntervalTime aTimeout,
 NS_IMETHODIMP TimerThread::Run()
 {
   nsAutoLock lock(mLock);
-  mProcessing = PR_TRUE;
 
-  while (mProcessing) {
+  while (!mShutdown) {
     PRIntervalTime now = PR_IntervalNow();
     nsTimerImpl *timer = nsnull;
 
@@ -225,7 +224,7 @@ NS_IMETHODIMP TimerThread::Run()
         timer = nsnull;
 
         lock.lock();
-        if (!mProcessing)
+        if (mShutdown)
           break;
 
         // Update now, as PostTimerEvent plus the locking may have taken a tick or two,
diff --git a/xpcom/threads/TimerThread.h b/xpcom/threads/TimerThread.h
index 01e1e14e9244..87beb7276422 100644
--- a/xpcom/threads/TimerThread.h
+++ b/xpcom/threads/TimerThread.h
@@ -83,7 +83,7 @@ private:
   PRLock *mLock;
   PRCondVar *mCondVar;
 
-  PRPackedBool mProcessing;
+  PRPackedBool mShutdown;
   PRPackedBool mWaiting;
 
   nsVoidArray mTimers;