diff -r d62633fea8ed -r 7b9898062c8f master/datagram.c
--- a/master/datagram.c	Mon Jan 26 11:58:35 2009 +0000
+++ b/master/datagram.c	Mon Jan 26 11:59:07 2009 +0000
@@ -113,8 +113,10 @@
  */
 void ec_datagram_clear(ec_datagram_t *datagram /**< EtherCAT datagram. */)
 {
-    if (datagram->data_origin == EC_ORIG_INTERNAL && datagram->data)
+    if (datagram->data_origin == EC_ORIG_INTERNAL && datagram->data) {
         kfree(datagram->data);
+    	datagram->data = NULL;
+    }
 }
 
 /*****************************************************************************/