diff --git a/timeoutd.c b/timeoutd.c
index 2af48f7..6ec4218 100644
--- a/timeoutd.c
+++ b/timeoutd.c
@@ -823,7 +823,7 @@ void check_idle()
     struct stat status;
     time_t idle, sesstime;
 
-    if (utmpp->ut_type != USER_PROCESS || kill(utmpp->ut_pid, 0)) /* if not user process, or if proc doesn't exist */
+    if (utmpp->ut_type != USER_PROCESS || kill(utmpp->ut_pid, 0) == -1) /* if not user process, or if proc doesn't exist */
         return;                 /* skip the utmp entry */
     strncpy(user, utmpp->ut_user, sizeof(user) - 1);    /* get user name */
     user[sizeof(user) - 1] = '\0';      /* null terminate user name string */