--- a/master/master.c	Mon Dec 06 11:42:48 2010 +0100
+++ b/master/master.c	Mon Dec 13 17:38:24 2010 +0100
@@ -796,6 +796,7 @@
             queue) {
         if (queued_datagram == datagram) {
             datagram->state = EC_DATAGRAM_QUEUED;
+            up(&master->io_sem);
             return;
         }
     }