diff --git a/mfbt/LinkedList.h b/mfbt/LinkedList.h
index a099d7597a..9d04e64c77 100644
--- a/mfbt/LinkedList.h
+++ b/mfbt/LinkedList.h
@@ -327,7 +327,8 @@ private:
   void setNextUnsafe(RawType aElem)
   {
     LinkedListElement *listElem = static_cast<LinkedListElement*>(aElem);
-    MOZ_ASSERT(!listElem->isInList());
+    if (listElem->isInList())
+      return;
 
     listElem->mNext = this->mNext;
     listElem->mPrev = this;
@@ -344,7 +345,8 @@ private:
   void setPreviousUnsafe(RawType aElem)
   {
     LinkedListElement<T>* listElem = static_cast<LinkedListElement<T>*>(aElem);
-    MOZ_ASSERT(!listElem->isInList());
+    if (listElem->isInList())
+      return;
 
     listElem->mNext = this;
     listElem->mPrev = this->mPrev;