diff --git a/deps/v8/src/handles/persistent-handles.cc b/deps/v8/src/handles/persistent-handles.cc
index 1a142038a75b..a566948ec034 100644
--- a/deps/v8/src/handles/persistent-handles.cc
+++ b/deps/v8/src/handles/persistent-handles.cc
@@ -124,6 +124,9 @@ void PersistentHandlesList::Remove(PersistentHandles* persistent_handles) {
 
 void PersistentHandlesList::Iterate(RootVisitor* visitor, Isolate* isolate) {
   isolate->heap()->safepoint()->AssertActive();
+  // Use the lock here because PersistentHandles could be dropped from threads
+  // without a LocalHeap.
+  base::MutexGuard guard(&persistent_handles_mutex_);
   for (PersistentHandles* current = persistent_handles_head_; current;
        current = current->next_) {
     current->Iterate(visitor);