diff --git a/src/acl.c b/src/acl.c
index d9475916e..b6e55ec26 100644
--- a/src/acl.c
+++ b/src/acl.c
@@ -1158,7 +1158,7 @@ struct acl_expr *parse_acl_expr(const char **args, char **err, struct arg_list *
 			expr->args[0].type = type;
 			expr->args[0].unresolved = 1;
 			expr->args[0].data.str.str = strdup("");
-			expr->args[0].data.str.len = 1;
+			expr->args[0].data.str.size = 1;
 			expr->args[0].data.str.len = 0;
 			arg_list_add(al, &expr->args[0], 0);