diff --git a/packages/runtime-dom/src/index.ts b/packages/runtime-dom/src/index.ts
index 0dfe9fba0..027bef11b 100644
--- a/packages/runtime-dom/src/index.ts
+++ b/packages/runtime-dom/src/index.ts
@@ -119,7 +119,7 @@ function normalizeContainer(
   }
   if (
     __DEV__ &&
-    container instanceof ShadowRoot &&
+    container instanceof window.ShadowRoot &&
     container.mode === 'closed'
   ) {
     warn(