--- a/dom/ipc/ProcessHangMonitor.cpp
+++ b/dom/ipc/ProcessHangMonitor.cpp
@@ -303,16 +303,17 @@ HangMonitorChild::InterruptCallback()
 
     mForcePaint = false;
   }
 
   if (forcePaint) {
     RefPtr<TabChild> tabChild = TabChild::FindTabChild(forcePaintTab);
     if (tabChild) {
       JS::AutoAssertOnGC aaogc(mContext);
+      JS::AutoAssertOnBarrier nobarrier(mContext);
       tabChild->ForcePaint(forcePaintEpoch);
     }
   }
 }
 
 void
 HangMonitorChild::Shutdown()
 {