--- a/gfx/layers/ipc/CanvasThread.cpp
+++ b/gfx/layers/ipc/CanvasThread.cpp
@@ -76,21 +76,16 @@ void CanvasThreadHolder::StaticRelease(
   // Note we can't just use NS_IsInCompositorThread() here because
   // sCompositorThreadHolder might have already gone.
   MOZ_ASSERT(threadHolder->mCompositorThreadKeepAlive->GetCompositorThread()
                  ->thread_id() == PlatformThread::CurrentId());
   threadHolder = nullptr;
 
   auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();
   if (lockedCanvasThreadHolder.ref()->mRefCnt == 1) {
-    MOZ_ASSERT(lockedCanvasThreadHolder.ref()
-                       ->mCanvasWorkers.forget()
-                       .take()
-                       ->Release() == 0,
-               "There should be no other references to mCanvasWorkers.");
     lockedCanvasThreadHolder.ref() = nullptr;
   }
 }
 
 /* static */
 void CanvasThreadHolder::ReleaseOnCompositorThread(
     already_AddRefed<CanvasThreadHolder> aCanvasThreadHolder) {
   auto lockedCanvasThreadHolder = sCanvasThreadHolder.Lock();