diff --git a/content/base/src/nsNodeUtils.cpp b/content/base/src/nsNodeUtils.cpp
index 23e70e335ab..70870b9ad37 100644
--- a/content/base/src/nsNodeUtils.cpp
+++ b/content/base/src/nsNodeUtils.cpp
@@ -218,7 +218,8 @@ nsNodeUtils::LastRelease(nsINode* aNode)
       static_cast<nsGenericHTMLFormElement*>(aNode)->ClearForm(true);
     }
 
-    if (aNode->IsElement() && aNode->AsElement()->IsHTML(nsGkAtoms::img)) {
+    if (aNode->IsElement() && aNode->AsElement()->IsHTML(nsGkAtoms::img) &&
+        aNode->HasFlag(ADDED_TO_FORM)) {
       HTMLImageElement* imageElem = static_cast<HTMLImageElement*>(aNode);
       imageElem->ClearForm(true);
     }