diff --git a/src/auth.c b/src/auth.c
index db1e6bb7..e7fbd9b3 100644
--- a/src/auth.c
+++ b/src/auth.c
@@ -1369,7 +1369,7 @@ void ssh_kbdint_free(ssh_kbdint kbd) {
 }
 
 void ssh_kbdint_clean(ssh_kbdint kbd) {
-    int i, n;
+    size_t i, n;
 
     if (kbd == NULL) {
         return;