diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index e698047f2e..5b20b4a773 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -475,7 +475,8 @@ static int custom_mount_check_all(void) {
                 if (path_equal(m->destination, "/") && arg_userns_mode != USER_NAMESPACE_NO) {
                         if (arg_userns_ownership != USER_NAMESPACE_OWNERSHIP_OFF)
                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
-                                                       "--private-users-ownership=own may not be combined with custom root mounts.");
+                                                       "--private-users-ownership=%s may not be combined with custom root mounts.",
+                                                       user_namespace_ownership_to_string(arg_userns_ownership));
                         if (arg_uid_shift == UID_INVALID)
                                 return log_error_errno(SYNTHETIC_ERRNO(EINVAL),
                                                        "--private-users with automatic UID shift may not be combined with custom root mounts.");