--- a/content/media/nsMediaCache.cpp
+++ b/content/media/nsMediaCache.cpp
@@ -460,16 +460,18 @@ nsMediaCacheStream::BlockList::NotifyBlo
     mEntries.GetEntry(e2Next)->mPrevBlock = aBlockIndex1;
   }
 
   // Fix hashtable keys. First remove stale entries.
   if (e1) {
     e1Prev = e1->mPrevBlock;
     e1Next = e1->mNextBlock;
     mEntries.RemoveEntry(aBlockIndex1);
+    // Refresh pointer after hashtable mutation.
+    e2 = mEntries.GetEntry(aBlockIndex2);
   }
   if (e2) {
     e2Prev = e2->mPrevBlock;
     e2Next = e2->mNextBlock;
     mEntries.RemoveEntry(aBlockIndex2);
   }
   // Put new entries back.
   if (e1) {