--- a/dom/media/MediaStreamGraph.cpp
+++ b/dom/media/MediaStreamGraph.cpp
@@ -1119,21 +1119,20 @@ void
 MediaStreamGraph::AssertOnGraphThreadOrNotRunning() const
 {
   // either we're on the right thread (and calling CurrentDriver() is safe),
   // or we're going to assert anyways, so don't cross-check CurrentDriver
 #ifdef DEBUG
   MediaStreamGraphImpl const * graph =
     static_cast<MediaStreamGraphImpl const *>(this);
   // if all the safety checks fail, assert we own the monitor
-  if (!graph->mDriver->OnThread()) {
-    if (!(graph->mDetectedNotRunning &&
-          NS_IsMainThread())) {
+  if (!(graph->mDetectedNotRunning ?
+        NS_IsMainThread() : graph->mDriver->OnThread()))
+  {
       graph->mMonitor.AssertCurrentThreadOwns();
-    }
   }
 #endif
 }
 
 bool
 MediaStreamGraphImpl::ShouldUpdateMainThread()
 {
   if (mRealtime) {