diff --git a/js/src/vm/Runtime.h b/js/src/vm/Runtime.h
index e4b020e0017..efef80f54db 100644
--- a/js/src/vm/Runtime.h
+++ b/js/src/vm/Runtime.h
@@ -672,7 +672,7 @@ namespace gc {
 class MarkingValidator;
 } // namespace gc
 
-typedef Vector<JS::Zone *, 1, SystemAllocPolicy> ZoneVector;
+typedef Vector<JS::Zone *, 4, SystemAllocPolicy> ZoneVector;
 
 class AutoLockForExclusiveAccess;
 class AutoPauseWorkersForGC;