diff --git a/dom/cache/StreamControl.cpp b/dom/cache/StreamControl.cpp
index aab176666..69a72d0b6 100644
--- a/dom/cache/StreamControl.cpp
+++ b/dom/cache/StreamControl.cpp
@@ -68,7 +68,8 @@ StreamControl::CloseAllReadStreams()
 {
   AssertOwningThread();
 
-  ReadStreamList::ForwardIterator iter(mReadStreamList);
+  auto readStreamList = mReadStreamList;
+  ReadStreamList::ForwardIterator iter(readStreamList);
   while (iter.HasMore()) {
     iter.GetNext()->CloseStream();
   }