diff --git a/mozilla/layout/style/nsStyleStruct.cpp b/mozilla/layout/style/nsStyleStruct.cpp
index 72c97ab3b68..c7a2a756449 100644
--- a/mozilla/layout/style/nsStyleStruct.cpp
+++ b/mozilla/layout/style/nsStyleStruct.cpp
@@ -1339,6 +1339,8 @@ PRBool nsStyleContentData::operator==(const nsStyleContentData& aOther)
   if (mType != aOther.mType)
     return PR_FALSE;
   if (mType == eStyleContentType_Image) {
+    if (!mContent.mImage || !aOther.mContent.mImage)
+      return mContent.mImage == aOther.mContent.mImage;
     PRBool eq;
     nsCOMPtr<nsIURI> thisURI, otherURI;
     mContent.mImage->GetURI(getter_AddRefs(thisURI));