diff --git a/engine/core/html/HTMLImportElement.cpp b/engine/core/html/HTMLImportElement.cpp
index 7c60928d099..dbd92bc3498 100644
--- a/engine/core/html/HTMLImportElement.cpp
+++ b/engine/core/html/HTMLImportElement.cpp
@@ -74,7 +74,7 @@ void HTMLImportElement::importChildWasDestroyed(HTMLImportChild* child)
 
 bool HTMLImportElement::isSync() const
 {
-    return true;
+    return !hasAttribute(HTMLNames::asyncAttr);
 }
 
 Element* HTMLImportElement::link()