--- a/mfbt/SplayTree.h
+++ b/mfbt/SplayTree.h
@@ -143,16 +143,18 @@ public:
     mRoot->mRight = last->mRight;
     if (mRoot->mLeft) {
       mRoot->mLeft->mParent = mRoot;
     }
     if (mRoot->mRight) {
       mRoot->mRight->mParent = mRoot;
     }
 
+    last->mLeft = nullptr;
+    last->mRight = nullptr;
     return last;
   }
 
   T* removeMin()
   {
     MOZ_ASSERT(mRoot, "No min to remove!");
 
     T* min = mRoot;