diff --git a/layout/base/nsCSSFrameConstructor.cpp b/layout/base/nsCSSFrameConstructor.cpp
index 4666f8fe82a..4892cb87c5f 100644
--- a/layout/base/nsCSSFrameConstructor.cpp
+++ b/layout/base/nsCSSFrameConstructor.cpp
@@ -5073,6 +5073,10 @@ nsCSSFrameConstructor::FindInputData(nsIContent* aContent,
   nsCOMPtr<nsIFormControl> control = do_QueryInterface(aContent);
   NS_ASSERTION(control, "input doesn't implement nsIFormControl?");
 
+  if (!control) { // Speculative parsing is screwing up somehow, dammit
+    return nsnull;
+  }
+
   return FindDataByInt(control->GetType(), aContent, aStyleContext,
                        sInputData, NS_ARRAY_LENGTH(sInputData));
 }