diff --git a/xpcom/base/nsMemoryImpl.cpp b/xpcom/base/nsMemoryImpl.cpp
index 27668a34a302..7d650d83fdd0 100644
--- a/xpcom/base/nsMemoryImpl.cpp
+++ b/xpcom/base/nsMemoryImpl.cpp
@@ -113,7 +113,7 @@ nsMemoryImpl::FlushMemory(const char16_t* aReason, bool aImmediate)
         }
     }
 
-    int32_t lastVal = sIsFlushing.exchange(1);
+    bool lastVal = sIsFlushing.exchange(true);
     if (lastVal)
         return NS_OK;
 
@@ -154,7 +154,7 @@ nsMemoryImpl::RunFlushers(const char16_t* aReason)
           nsCOMPtr<nsIObserver> observer;
           bool loop = true;
 
-          while (NS_SUCCEEDED(e->HasMoreElements(&loop)) && loop) 
+          while (NS_SUCCEEDED(e->HasMoreElements(&loop)) && loop)
           {
               e->GetNext(getter_AddRefs(observer));
 
@@ -166,7 +166,7 @@ nsMemoryImpl::RunFlushers(const char16_t* aReason)
         }
     }
 
-    sIsFlushing = 0;
+    sIsFlushing = false;
     return NS_OK;
 }
 
@@ -182,7 +182,7 @@ nsMemoryImpl::FlushEvent::Run()
     return NS_OK;
 }
 
-mozilla::Atomic<int32_t>
+mozilla::Atomic<bool>
 nsMemoryImpl::sIsFlushing;
 
 PRIntervalTime
diff --git a/xpcom/base/nsMemoryImpl.h b/xpcom/base/nsMemoryImpl.h
index 2d04c1bdc8b6..eba170afa2e8 100644
--- a/xpcom/base/nsMemoryImpl.h
+++ b/xpcom/base/nsMemoryImpl.h
@@ -38,7 +38,7 @@ protected:
         const char16_t* mReason;
     };
 
-    static mozilla::Atomic<int32_t> sIsFlushing;
+    static mozilla::Atomic<bool> sIsFlushing;
     static FlushEvent sFlushEvent;
     static PRIntervalTime sLastFlushTime;
 };
diff --git a/xpcom/threads/TimerThread.cpp b/xpcom/threads/TimerThread.cpp
index e0934423a77b..0303283076cb 100644
--- a/xpcom/threads/TimerThread.cpp
+++ b/xpcom/threads/TimerThread.cpp
@@ -20,7 +20,7 @@ using namespace mozilla;
 NS_IMPL_ISUPPORTS2(TimerThread, nsIRunnable, nsIObserver)
 
 TimerThread::TimerThread() :
-  mInitInProgress(0),
+  mInitInProgress(false),
   mInitialized(false),
   mMonitor("TimerThread.mMonitor"),
   mShutdown(false),
@@ -84,7 +84,7 @@ nsresult TimerThread::Init()
     return NS_OK;
   }
 
-  if (mInitInProgress.exchange(1) == 0) {
+  if (mInitInProgress.exchange(true) == false) {
     // We hold on to mThread to keep the thread alive.
     nsresult rv = NS_NewThread(getter_AddRefs(mThread), this);
     if (NS_FAILED(rv)) {
@@ -244,7 +244,7 @@ NS_IMETHODIMP TimerThread::Run()
             if (NS_FAILED(timer->PostTimerEvent())) {
               nsrefcnt rc;
               NS_RELEASE2(timer, rc);
-            
+
               // The nsITimer interface requires that its users keep a reference
               // to the timers they use while those timers are initialized but
               // have not yet fired.  If this ever happens, it is a bug in the
diff --git a/xpcom/threads/TimerThread.h b/xpcom/threads/TimerThread.h
index 81d4f6cd9cac..3e76bfc77887 100644
--- a/xpcom/threads/TimerThread.h
+++ b/xpcom/threads/TimerThread.h
@@ -37,7 +37,7 @@ public:
   NS_DECL_THREADSAFE_ISUPPORTS
   NS_DECL_NSIRUNNABLE
   NS_DECL_NSIOBSERVER
-  
+
   NS_HIDDEN_(nsresult) Init();
   NS_HIDDEN_(nsresult) Shutdown();
 
@@ -56,7 +56,7 @@ public:
 private:
   ~TimerThread();
 
-  mozilla::Atomic<int32_t> mInitInProgress;
+  mozilla::Atomic<bool> mInitInProgress;
   bool    mInitialized;
 
   // These two internal helper methods must be called while mLock is held.
@@ -72,7 +72,7 @@ private:
   bool mShutdown;
   bool mWaiting;
   bool mSleeping;
-  
+
   nsTArray<nsTimerImpl*> mTimers;
 };