diff --git a/src/yunohost/user.py b/src/yunohost/user.py
index 39a2d8f15..fd67314d8 100644
--- a/src/yunohost/user.py
+++ b/src/yunohost/user.py
@@ -165,8 +165,8 @@ def user_create(operation_logger, username, firstname, lastname, mail, password,
     operation_logger.start()
 
     # Get random UID/GID
-    all_uid = {x.pw_uid for x in pwd.getpwall()}
-    all_gid = {x.gr_gid for x in grp.getgrall()}
+    all_uid = {str(x.pw_uid) for x in pwd.getpwall()}
+    all_gid = {str(x.gr_gid) for x in grp.getgrall()}
 
     uid_guid_found = False
     while not uid_guid_found: