diff --git a/containers.mllib b/containers.mllib
index ae106d5d..7d377ec1 100644
--- a/containers.mllib
+++ b/containers.mllib
@@ -5,6 +5,7 @@ Cache
 FlatHashtbl
 FHashtbl
 FQueue
+Hashset
 SplayTree
 PHashtbl
 Heap