diff --git a/HISTORY b/HISTORY
index 2cdf82f..fb97152 100644
--- a/HISTORY
+++ b/HISTORY
@@ -1,10 +1,11 @@
 
-Version 1.21  2015-09-08
+Version 1.21  2015-09-13
   * ini_file_reader support annotation function
   * correct PTHREAD_MUTEX_ERRORCHECK define
   * support 32 bit OS
   * allow_ips support CIDR addresses such as 172.16.12.0/22
   * add function get_first_local_ip
+  * ioevent for BSD ok
 
 Version 1.20  2015-08-06
   * add GEO function get_line_distance_km
diff --git a/src/ioevent.c b/src/ioevent.c
index 7454b7c..d432a2e 100644
--- a/src/ioevent.c
+++ b/src/ioevent.c
@@ -47,6 +47,7 @@ int ioevent_init(IOEventPoller *ioevent, const int size,
   ioevent->poll_fd = kqueue();
   bytes = sizeof(struct kevent) * size;
   ioevent->events = (struct kevent *)malloc(bytes);
+  ioevent->care_events = 0;
 #elif IOEVENT_USE_PORT
   ioevent->poll_fd = port_create();
   bytes = sizeof(port_event_t) * size;
@@ -92,6 +93,7 @@ int ioevent_attach(IOEventPoller *ioevent, const int fd, const int e,
   if (e & IOEVENT_WRITE) {
     EV_SET(&ev[n++], fd, EVFILT_WRITE, EV_ADD | ioevent->extra_events, 0, 0, data);
   }
+  ioevent->care_events = e;
   return kevent(ioevent->poll_fd, ev, n, NULL, 0, NULL);
 #elif IOEVENT_USE_PORT
   return port_associate(ioevent->poll_fd, PORT_SOURCE_FD, fd, e, data);
@@ -111,18 +113,23 @@ int ioevent_modify(IOEventPoller *ioevent, const int fd, const int e,
   struct kevent ev[2];
   int n = 0;
   if (e & IOEVENT_READ) {
-    EV_SET(&ev[n++], fd, EVFILT_READ, EV_ADD | ioevent->extra_events, 0, 0, data);
+     if (!(ioevent->care_events & IOEVENT_READ)) {
+        EV_SET(&ev[n++], fd, EVFILT_READ, EV_ADD | ioevent->extra_events, 0, 0, data);
+     }
   }
-  else {
-    EV_SET(&ev[n++], fd, EVFILT_READ, EV_DELETE, 0, 0, data);
+  else if ((ioevent->care_events & IOEVENT_READ)) {
+    EV_SET(&ev[n++], fd, EVFILT_READ, EV_DELETE, 0, 0, NULL);
   }
 
   if (e & IOEVENT_WRITE) {
-    EV_SET(&ev[n++], fd, EVFILT_WRITE, EV_ADD | ioevent->extra_events, 0, 0, data);
+    if (!(ioevent->care_events & IOEVENT_WRITE)) {
+      EV_SET(&ev[n++], fd, EVFILT_WRITE, EV_ADD | ioevent->extra_events, 0, 0, data);
+    }
   }
-  else {
-    EV_SET(&ev[n++], fd, EVFILT_WRITE, EV_DELETE, 0, 0, data);
+  else if ((ioevent->care_events & IOEVENT_WRITE)) {
+    EV_SET(&ev[n++], fd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
   }
+  ioevent->care_events = e;
   return kevent(ioevent->poll_fd, ev, n, NULL, 0, NULL);
 #elif IOEVENT_USE_PORT
   return port_associate(ioevent->poll_fd, PORT_SOURCE_FD, fd, e, data);
@@ -133,10 +140,19 @@ int ioevent_detach(IOEventPoller *ioevent, const int fd)
 {
 #if IOEVENT_USE_EPOLL
   return epoll_ctl(ioevent->poll_fd, EPOLL_CTL_DEL, fd, NULL);
+#elif IOEVENT_USE_KQUEUE
+  struct kevent ev[2];
+  int n = 0;
+  if ((ioevent->care_events & IOEVENT_READ)) {
+    EV_SET(&ev[n++], fd, EVFILT_READ, EV_DELETE, 0, 0, NULL);
+  }
+  if ((ioevent->care_events & IOEVENT_WRITE)) {
+    EV_SET(&ev[n++], fd, EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
+  }
+  ioevent->care_events = 0;
+  return kevent(ioevent->poll_fd, ev, n, NULL, 0, NULL);
 #elif IOEVENT_USE_PORT
   return port_dissociate(ioevent->poll_fd, PORT_SOURCE_FD, fd);
-#else
-  return 0;
 #endif
 }
 
diff --git a/src/ioevent.h b/src/ioevent.h
index 823a3a5..543a584 100644
--- a/src/ioevent.h
+++ b/src/ioevent.h
@@ -64,6 +64,7 @@ typedef struct ioevent_puller {
 #elif IOEVENT_USE_KQUEUE
     struct kevent *events;
     struct timespec timeout;
+    int care_events;
 #elif IOEVENT_USE_PORT
     port_event_t *events;
     timespec_t timeout;