diff --git a/reftable/iter.c b/reftable/iter.c
index 97a4642ed5..1d99fe4f7d 100644
--- a/reftable/iter.c
+++ b/reftable/iter.c
@@ -25,17 +25,17 @@ int iterator_next(struct reftable_iterator *it, struct reftable_record *rec)
 	return it->ops->next(it->iter_arg, rec);
 }
 
-static int empty_iterator_seek(void *arg, struct reftable_record *want)
+static int empty_iterator_seek(void *arg UNUSED, struct reftable_record *want UNUSED)
 {
 	return 0;
 }
 
-static int empty_iterator_next(void *arg, struct reftable_record *rec)
+static int empty_iterator_next(void *arg UNUSED, struct reftable_record *rec UNUSED)
 {
 	return 1;
 }
 
-static void empty_iterator_close(void *arg)
+static void empty_iterator_close(void *arg UNUSED)
 {
 }