diff --git a/user_channel/passwd_mgr.hpp b/user_channel/passwd_mgr.hpp
index ed76efa..4c94480 100644
--- a/user_channel/passwd_mgr.hpp
+++ b/user_channel/passwd_mgr.hpp
@@ -17,6 +17,7 @@
 #include <openssl/evp.h>
 
 #include <ctime>
+#include <string>
 #include <unordered_map>
 #include <vector>