diff --git a/test-oop.c b/test-oop.c
index c1f5281fe3b4306aa2bbdb47d1ed3e0537982b56..abbd5ae5c5a2de712d8e6622f37d7cc09a0b54ae 100644
--- a/test-oop.c
+++ b/test-oop.c
@@ -179,8 +179,7 @@ static void *stop_readline(oop_source *src,int sig,void *data) {
 
 static void add_readline(oop_source *src) {
 	rl_callback_handler_install(
-		(char *) "> ", /* readline isn't const-correct */
-		(VFunction *) on_readline);
+		"> ", (rl_vcpfunc_t *) on_readline);
 	oop_readline_register(src);
 	src->on_signal(src,SIGQUIT,stop_readline,NULL);
 }