--- a/gfx/layers/d3d11/HelpersD3D11.h
+++ b/gfx/layers/d3d11/HelpersD3D11.h
@@ -12,19 +12,17 @@
 namespace mozilla {
 namespace layers {
 
 template <typename T> static inline bool
 WaitForGPUQuery(ID3D11Device* aDevice, ID3D11DeviceContext* aContext, ID3D11Query* aQuery, T* aOut)
 {
   TimeStamp start = TimeStamp::Now();
   while (aContext->GetData(aQuery, aOut, sizeof(*aOut), 0) != S_OK) {
-    if (aDevice->GetDeviceRemovedReason() != S_OK) {
-      return false;
-    }
+    MOZ_ASSERT(aDevice->GetDeviceRemovedReason() == S_OK);
     if (TimeStamp::Now() - start > TimeDuration::FromSeconds(2)) {
       return false;
     }
     Sleep(0);
   }
   return true;
 }