diff --git a/cache/mapcache.h b/cache/mapcache.h
index e1301d8..0cd6089 100644
--- a/cache/mapcache.h
+++ b/cache/mapcache.h
@@ -4,6 +4,7 @@
 #include <set>
 #include <shared_mutex>
 #include <optional>
+#include <string>
 
 /* Thread-Safe Key-Value store */
 template <class T> class MapCache