diff --git a/dom/html/nsGenericHTMLElement.cpp b/dom/html/nsGenericHTMLElement.cpp
index 06950b3e220..ec02dcaed72 100644
--- a/dom/html/nsGenericHTMLElement.cpp
+++ b/dom/html/nsGenericHTMLElement.cpp
@@ -1978,7 +1978,7 @@ void nsGenericHTMLFormElement::BeforeSetAttr(int32_t aNameSpaceID,
                                              bool aNotify) {
   if (aNameSpaceID == kNameSpaceID_None && IsFormAssociatedElement()) {
     nsAutoString tmp;
-    HTMLFormElement* form = GetFormInternal();
+    HTMLFormElement* form = GetFormIfRegistered();
 
     // remove the control from the hashtable as needed
 
@@ -2034,7 +2034,7 @@ void nsGenericHTMLFormElement::AfterSetAttr(
         // Ensure that empty @form value clears the form owner.
         ClearForm(true, false);
       }
-    } else if (HTMLFormElement* form = GetFormInternal()) {
+    } else if (HTMLFormElement* form = GetFormIfRegistered()) {
       // add the control to the hashtable as needed
       if (aName == nsGkAtoms::type) {
         nsAutoString tmp;
diff --git a/dom/html/nsGenericHTMLElement.h b/dom/html/nsGenericHTMLElement.h
index 11b7af57dd4..08f5ca5a519 100644
--- a/dom/html/nsGenericHTMLElement.h
+++ b/dom/html/nsGenericHTMLElement.h
@@ -1120,6 +1120,10 @@ class nsGenericHTMLFormElement : public nsGenericHTMLElement {
     return nullptr;
   }
 
+  mozilla::dom::HTMLFormElement* GetFormIfRegistered() const {
+    return HasFlag(ADDED_TO_FORM) ? GetFormInternal() : nullptr;
+  }
+
   virtual mozilla::dom::HTMLFieldSetElement* GetFieldSetInternal() const {
     return nullptr;
   }