diff --git a/extra/mariabackup/xtrabackup.cc b/extra/mariabackup/xtrabackup.cc
index 04e33fa389e..375d8845a2a 100644
--- a/extra/mariabackup/xtrabackup.cc
+++ b/extra/mariabackup/xtrabackup.cc
@@ -3030,7 +3030,7 @@ xb_validate_name(
 		exit(EXIT_FAILURE);
 	}
 	p = strpbrk(name, "/\\~");
-	if (p && p - name < NAME_LEN) {
+	if (p && (uint) (p - name) < NAME_LEN) {
 		msg("mariabackup: name `%s` is not valid.\n", name);
 		exit(EXIT_FAILURE);
 	}