diff --git a/ref-filter.c b/ref-filter.c
index e39f505a81..4d0df546da 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -578,7 +578,7 @@ static int trailers_atom_parser(struct ref_format *format UNUSED,
 				strbuf_addf(err, _("expected %%(trailers:key=<value>)"));
 			else
 				strbuf_addf(err, _("unknown %%(trailers) argument: %s"), invalid_arg);
-			free((char *)invalid_arg);
+			free(invalid_arg);
 			return -1;
 		}
 	}