--- libev/ev_epoll.c	2010/03/23 23:45:12	1.50
+++ libev/ev_epoll.c	2010/04/21 13:13:18	1.51
@@ -90,7 +90,7 @@
   ev.events   = (nev & EV_READ  ? EPOLLIN  : 0)
               | (nev & EV_WRITE ? EPOLLOUT : 0);
 
-  if (expect_true (!epoll_ctl (backend_fd, oev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
+  if (expect_true (!epoll_ctl (backend_fd, oev && oldmask != nev ? EPOLL_CTL_MOD : EPOLL_CTL_ADD, fd, &ev)))
     return;
 
   if (expect_true (errno == ENOENT))