--- libev/ev.c	2007/11/11 02:26:47	1.99
+++ libev/ev.c	2007/11/11 04:02:54	1.100
@@ -1463,7 +1463,7 @@
 ev_prepare_stop (EV_P_ struct ev_prepare *w)
 {
   ev_clear_pending (EV_A_ (W)w);
-  if (ev_is_active (w))
+  if (!ev_is_active (w))
     return;
 
   prepares [((W)w)->active - 1] = prepares [--preparecnt];