diff --git a/lib/coroutine.h b/lib/coroutine.h
index f64a9540..93a41233 100644
--- a/lib/coroutine.h
+++ b/lib/coroutine.h
@@ -18,5 +18,6 @@ void coro_resume(coroutine *c);
 
 struct birdsock;
 int coro_sk_read(struct birdsock *s);
+void coro_sk_write(struct birdsock *s, unsigned len);
 
 #endif
diff --git a/lib/socket.h b/lib/socket.h
index 00e4a29c..d961841e 100644
--- a/lib/socket.h
+++ b/lib/socket.h
@@ -83,6 +83,7 @@ typedef struct birdsock {
   struct ssh_sock *ssh;			/* Used in SK_SSH */
 
   struct coroutine *rx_coroutine;
+  struct coroutine *tx_coroutine;
 } sock;
 
 sock *sock_new(pool *);			/* Allocate new socket */
diff --git a/nest/cli.c b/nest/cli.c
index 986b2880..f4b7628c 100644
--- a/nest/cli.c
+++ b/nest/cli.c
@@ -245,8 +245,7 @@ cli_write(cli *c)
       s->tbuf = o->outpos;
       o->outpos = o->wpos;
 
-      if (sk_send(s, len) <= 0)
-	return;
+      coro_sk_write(s, len);
 
       c->tx_pos = o->next;
     }
@@ -264,12 +263,6 @@ cli_write_trigger(cli *c)
     cli_write(c);
 }
 
-static void
-cli_tx_hook(sock *s)
-{
-  cli_write(s->data);
-}
-
 static void
 cli_err_hook(sock *s, int err)
 {
@@ -540,7 +533,6 @@ cli_new(sock *s)
 
   s->pool = c->pool;		/* We need to have all the socket buffers allocated in the cli pool */
   rmove(s, c->pool);
-  s->tx_hook = cli_tx_hook;
   s->err_hook = cli_err_hook;
   s->data = c;
 
diff --git a/sysdep/unix/coroutine.c b/sysdep/unix/coroutine.c
index c5a2ba73..fc650a57 100644
--- a/sysdep/unix/coroutine.c
+++ b/sysdep/unix/coroutine.c
@@ -146,6 +146,7 @@ static void
 coro_free(resource *r)
 {
   coroutine *c = (coroutine *) r;
+  ASSERT(coro_current != c);
   pthread_cancel(c->thread);
   pthread_join(c->thread, NULL);
 }
@@ -246,6 +247,14 @@ coro_sk_rx_hook(sock *sk, uint size UNUSED)
   return 0;
 }
 
+static void
+coro_sk_tx_hook(sock *sk)
+{
+  ASSERT(sk->tx_coroutine);
+  ASSERT(!coro_current);
+  coro_resume(sk->tx_coroutine);
+}
+
 int
 coro_sk_read(sock *s)
 {
@@ -256,3 +265,15 @@ coro_sk_read(sock *s)
   s->rx_hook = NULL;
   return s->rpos - s->rbuf;
 }
+
+void
+coro_sk_write(sock *s, unsigned len)
+{
+  ASSERT(coro_current);
+  s->tx_coroutine = coro_current;
+  s->tx_hook = coro_sk_tx_hook;
+  s->ttx = s->tbuf;
+  s->tpos = s->tbuf + len;
+  coro_suspend();
+  s->tx_hook = NULL;
+}