diff --git a/content/html/document/src/nsHTMLContentSink.cpp b/content/html/document/src/nsHTMLContentSink.cpp
index 707b1975484..d1ecdad73e5 100644
--- a/content/html/document/src/nsHTMLContentSink.cpp
+++ b/content/html/document/src/nsHTMLContentSink.cpp
@@ -1193,7 +1193,7 @@ SinkContext::CloseContainer(const nsHTMLTag aTag, PRBool aMalformed)
   --mStackPos;
   nsHTMLTag nodeType = mStack[mStackPos].mType;
 
-  NS_ASSERTION(nodeType == aTag,
+  NS_ASSERTION(nodeType == eHTMLTag_form || nodeType == aTag,
                "Tag mismatch.  Closing tag on wrong context or something?");
 
   nsGenericHTMLElement* content = mStack[mStackPos].mContent;