diff --git a/fsw_set.h b/fsw_set.h
index 99cbd94..b5317b9 100644
--- a/fsw_set.h
+++ b/fsw_set.h
@@ -10,7 +10,7 @@ template <typename K>
 using fsw_hash_set = unordered_set<K>;
 
 #else
-#include <map>
+#include <set>
 
 template <typename K>
 using fsw_hash_set = set<K>;