diff --git a/io.h b/io.h
index 77f920e..780f34a 100644
--- a/io.h
+++ b/io.h
@@ -55,7 +55,7 @@ void io_dontwantwrite(int64 d);
 
 void io_wait();
 void io_waituntil(tai6464 t);
-void io_waituntil2(int64 milliseconds);
+int64 io_waituntil2(int64 milliseconds);
 void io_check();
 
 /* signal that read/accept/whatever returned EAGAIN */