diff --git a/dom/base/GlobalTeardownObserver.cpp b/dom/base/GlobalTeardownObserver.cpp
index 15c4333e05e..d5e6029e079 100644
--- a/dom/base/GlobalTeardownObserver.cpp
+++ b/dom/base/GlobalTeardownObserver.cpp
@@ -65,7 +65,13 @@ nsresult GlobalTeardownObserver::CheckCurrentGlobalCorrectness() const {
     }
   }
 
-  if (mParentObject->IsDying() && !NS_IsMainThread()) {
+  if (NS_IsMainThread()) {
+    return NS_OK;
+  }
+
+  // Not on main thread, might check if is on the global's owning thread before
+  // calling IsDying().
+  if (mParentObject->IsDying()) {
     return NS_ERROR_FAILURE;
   }