diff --git a/site_ansto/hardsup/nhq200util.c b/site_ansto/hardsup/nhq200util.c
index dbc7e8a4..73b418d7 100644
--- a/site_ansto/hardsup/nhq200util.c
+++ b/site_ansto/hardsup/nhq200util.c
@@ -271,6 +271,9 @@ int NHQ200_Setup(pNHQ200 self, int iControl) /* Operations common to both Open a
   char pCommand[20];
   char pReply[132];
 
+  if (!self || !self->controller || !self->controller->pSock)
+    return NHQ200__BADCOM;
+
   /* MJL enable RS232 debugging mode. */
   setRS232Debug(self->controller,1);
   printf("***RS232 debug mode enabled for NHQ200***\n");fflush(stdout);