diff --git a/builtin/count-objects.c b/builtin/count-objects.c
index 97cdfb0ac5..2d4bb5e8d0 100644
--- a/builtin/count-objects.c
+++ b/builtin/count-objects.c
@@ -82,7 +82,7 @@ static int count_cruft(const char *basename UNUSED, const char *path,
 	return 0;
 }
 
-static int print_alternate(struct object_directory *odb, void *data)
+static int print_alternate(struct object_directory *odb, void *data UNUSED)
 {
 	printf("alternate: ");
 	quote_c_style(odb->path, NULL, stdout, 0);