--- a/parser/html/nsHtml5TreeOperation.cpp
+++ b/parser/html/nsHtml5TreeOperation.cpp
@@ -255,19 +255,20 @@ nsHtml5TreeOperation::AppendToDocument(n
   nsIDocument* doc = aBuilder->GetDocument();
   PRUint32 childCount = doc->GetChildCount();
   rv = doc->AppendChildTo(aNode, PR_FALSE);
   NS_ENSURE_SUCCESS(rv, rv);
   nsNodeUtils::ContentInserted(doc, aNode, childCount);
 
   NS_ASSERTION(!nsContentUtils::IsSafeToRunScript(),
                "Someone forgot to block scripts");
-  nsContentUtils::AddScriptRunner(
-    new nsDocElementCreatedNotificationRunner(doc));
-
+  if (aNode->IsElement()) {
+    nsContentUtils::AddScriptRunner(
+        new nsDocElementCreatedNotificationRunner(doc));
+  }
   return rv;
 }
 
 nsresult
 nsHtml5TreeOperation::Perform(nsHtml5TreeOpExecutor* aBuilder,
                               nsIContent** aScriptElement)
 {
   nsresult rv = NS_OK;