--- a/js/src/threading/windows/ConditionVariable.cpp
+++ b/js/src/threading/windows/ConditionVariable.cpp
@@ -263,17 +263,17 @@ public:
       releaseSleepWakeupSemaphore = true;
 
     } else if (wakeupMode == WAKEUP_MODE_ALL && sleepersCount == 0) {
       // If this was the last thread waking up in response to a
       // notify_all, clear the wakeup mode and reset the wake-all event.
       // A race condition similar to the case described above could
       // occur, so waitResult could be WAIT_TIMEOUT, but that doesn't
       // matter for the actions that need to be taken.
-      MOZ_RELEASE_ASSERT(waitResult = WAIT_OBJECT_0 + 1 ||
+      MOZ_RELEASE_ASSERT(waitResult == WAIT_OBJECT_0 + 1 ||
                          waitResult == WAIT_TIMEOUT);
 
       BOOL success = ResetEvent(wakeAllEvent_);
       MOZ_RELEASE_ASSERT(success);
 
       sleepersCountAndWakeupMode_ = 0 | WAKEUP_MODE_NONE;
 
       // The broadcasting thread has acquired the enter-wakeup semaphore