diff --git a/src/hashset.hpp b/src/hashset.hpp
index 6efd4dd9..7acfa23f 100644
--- a/src/hashset.hpp
+++ b/src/hashset.hpp
@@ -41,6 +41,7 @@ public:
   ~HashSet()
   {
     kh_destroy(hashset,_set);
+    str_set_cleanup(&_str_set);
   }
 
   inline