diff -r c9e2c3be294e -r 4e8d56d6f12a master/datagram.c
--- a/master/datagram.c	Wed Oct 28 14:59:34 2009 +0100
+++ b/master/datagram.c	Thu Oct 29 17:28:49 2009 +0100
@@ -116,6 +116,8 @@
  */
 void ec_datagram_clear(ec_datagram_t *datagram /**< EtherCAT datagram. */)
 {
+    ec_datagram_unqueue(datagram);
+
     if (datagram->data_origin == EC_ORIG_INTERNAL && datagram->data) {
         kfree(datagram->data);
         datagram->data = NULL;
@@ -124,6 +126,17 @@
 
 /*****************************************************************************/
 
+/** Unqueue datagram.
+ */
+void ec_datagram_unqueue(ec_datagram_t *datagram /**< EtherCAT datagram. */)
+{
+    if (!list_empty(&datagram->queue)) {
+        list_del_init(&datagram->queue);
+    }
+}
+
+/*****************************************************************************/
+
 /** Allocates internal payload memory.
  *
  * If the allocated memory is already larger than requested, nothing ist done.