diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
index 060ea33690f8..7daa9bbaa25c 100644
--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -1598,7 +1598,7 @@ PerThreadData::runtimeFromMainThread()
 inline JSRuntime *
 PerThreadData::runtimeIfOnOwnerThread()
 {
-    return CurrentThreadCanAccessRuntime(runtime_) ? runtime_ : nullptr;
+    return (runtime_ && CurrentThreadCanAccessRuntime(runtime_)) ? runtime_ : nullptr;
 }
 
 inline bool