--- a/master/master.c	Tue Dec 04 11:57:55 2012 +0100
+++ b/master/master.c	Tue Dec 04 12:09:42 2012 +0100
@@ -415,6 +415,7 @@
     ec_slave_config_t *sc, *next;
 
     master->dc_ref_config = NULL;
+    master->fsm.sdo_request = NULL; // mark sdo_request as invalid
 
     list_for_each_entry_safe(sc, next, &master->configs, list) {
         list_del(&sc->list);