diff --git a/GNUmakefile b/GNUmakefile
index c2c0d8c..8b54f64 100644
--- a/GNUmakefile
+++ b/GNUmakefile
@@ -60,7 +60,7 @@ $(DNS_OBJS): dns.h stralloc.h taia.h tai.h uint64.h iopause.h
 $(CASE_OBJS): case.h
 $(ARRAY_OBJS): uint64.h array.h
 $(MULT_OBJS): uint64.h uint32.h uint16.h safemult.h
-$(IO_OBJS): uint64.h array.h io.h io_internal.h taia.h tai.h
+$(IO_OBJS): uint64.h array.h io.h io_internal.h taia.h tai.h haveepoll.h havekqueue.h
 
 iopause.o: select.h
 openreadclose.o readclose.o: readclose.h
diff --git a/io/io_fd.c b/io/io_fd.c
index 5969a35..5ed8d8e 100644
--- a/io/io_fd.c
+++ b/io/io_fd.c
@@ -2,6 +2,12 @@
 #include <fcntl.h>
 
 #include "io_internal.h"
+#ifdef HAVE_KQUEUE
+#include <sys/event.h>
+#endif
+#ifdef HAVE_EPOLL
+#include <sys/epoll.h>
+#endif
 
 /* put d on internal data structure, return 1 on success, 0 on error */
 int io_fd(int64 d) {
@@ -13,5 +19,17 @@ int io_fd(int64 d) {
   e->inuse=1;
   if (r&O_NDELAY) e->nonblock=1;
   e->next_read=e->next_write=-1;
+  if (io_waitmode==UNDECIDED) {
+#if defined(HAVE_EPOLL)
+    io_master=epoll_create(1000);
+    if (io_master!=-1) io_waitmode=EPOLL;
+#endif
+#if defined(HAVE_KQUEUE)
+    if (io_waitmode==POLL) {	/* who knows, maybe someone supports both one day */
+      io_master=kqueue();
+      if (io_master!=-1) io_waitmode=KQUEUE;
+    }
+#endif
+  }
   return 1;
 }
diff --git a/io/io_wantread.c b/io/io_wantread.c
index c136514..0993be9 100644
--- a/io/io_wantread.c
+++ b/io/io_wantread.c
@@ -2,10 +2,38 @@
 #include <fcntl.h>
 #include <errno.h>
 #include "io_internal.h"
+#ifdef HAVE_KQUEUE
+#include <sys/types.h>
+#include <sys/event.h>
+#include <sys/time.h>
+#endif
+#ifdef HAVE_EPOLL
+#include <sys/epoll.h>
+#endif
 
 void io_wantread(int64 d) {
+  int newfd;
   io_entry* e=array_get(&io_fds,sizeof(io_entry),d);
   if (!e) return;
-  if (!e->wantread && !e->wantwrite) ++io_wanted_fds;
+  newfd=(!e->wantread && !e->wantwrite);
+  io_wanted_fds+=newfd;
+#ifdef HAVE_EPOLL
+  if (io_waitmode==EPOLL) {
+    struct epoll_event x;
+    x.events=EPOLLIN;
+    if (e->wantwrite) x.events|=EPOLLOUT;
+    x.data.fd=d;
+    epoll_ctl(io_master,newfd?EPOLL_CTL_ADD:EPOLL_CTL_MOD,d,&x);
+  }
+#endif
+#ifdef HAVE_KQUEUE
+  if (io_waitmode==KQUEUE) {
+    struct kevent kev;
+    struct timespec ts;
+    EV_SET(&kev, d, EVFILT_READ, EV_ADD|EV_ENABLE, 0, 0, 0);
+    ts.tv_sec=0; ts.tv_nsec=0;
+    kevent(io_master,&kev,1,0,0,&ts);
+  }
+#endif
   e->wantread=1;
 }
diff --git a/io/io_wantwrite.c b/io/io_wantwrite.c
index 127b4c5..2bcb0e3 100644
--- a/io/io_wantwrite.c
+++ b/io/io_wantwrite.c
@@ -2,10 +2,38 @@
 #include <fcntl.h>
 #include <errno.h>
 #include "io_internal.h"
+#ifdef HAVE_KQUEUE
+#include <sys/types.h>
+#include <sys/event.h>
+#include <sys/time.h>
+#endif
+#ifdef HAVE_EPOLL
+#include <sys/epoll.h>
+#endif
 
 void io_wantwrite(int64 d) {
+  int newfd;
   io_entry* e=array_get(&io_fds,sizeof(io_entry),d);
   if (!e) return;
-  if (!e->wantread && !e->wantwrite) ++io_wanted_fds;
+  newfd=(!e->wantread && !e->wantwrite);
+  io_wanted_fds+=newfd;
+#ifdef HAVE_EPOLL
+  if (io_waitmode==EPOLL) {
+    struct epoll_event x;
+    x.events=EPOLLOUT;
+    if (e->wantread) x.events|=EPOLLIN;
+    x.data.fd=d;
+    epoll_ctl(io_master,newfd?EPOLL_CTL_ADD:EPOLL_CTL_MOD,d,&x);
+  }
+#endif
+#ifdef HAVE_KQUEUE
+  if (io_waitmode==KQUEUE) {
+    struct kevent kev;
+    struct timespec ts;
+    EV_SET(&kev, d, EVFILT_WRITE, EV_ADD|EV_ENABLE, 0, 0, 0);
+    ts.tv_sec=0; ts.tv_nsec=0;
+    kevent(io_master,&kev,1,0,0,&ts);
+  }
+#endif
   e->wantwrite=1;
 }
diff --git a/io_internal.h b/io_internal.h
index ba75b11..64fedf4 100644
--- a/io_internal.h
+++ b/io_internal.h
@@ -1,5 +1,7 @@
 #include "io.h"
 #include "array.h"
+#include "haveepoll.h"
+#include "havekqueue.h"
 
 typedef struct {
   unsigned int wantread:1;
@@ -20,4 +22,19 @@ array io_pollfds;
 unsigned long first_readable;
 unsigned long first_writeable;
 
+enum {
+  UNDECIDED,
+  POLL
+#ifdef HAVE_KQUEUE
+  ,KQUEUE
+#endif
+#ifdef HAVE_EPOLL
+  ,EPOLL
+#endif
+} io_waitmode;
+
+#if defined(HAVE_KQUEUE) || defined(HAVE_EPOLL)
+int io_master;
+#endif
+
 int64 io_waituntil2(int64 milliseconds);