diff --git a/library/BSSMAP_Emulation.ttcn b/library/BSSMAP_Emulation.ttcn
index 55ce2fb..3816ed7 100644
--- a/library/BSSMAP_Emulation.ttcn
+++ b/library/BSSMAP_Emulation.ttcn
@@ -406,7 +406,7 @@
 		var BSSAP_ConnHdlr client := null;
 		client := f_imsi_table_find(bssap.pdu.bssmap.paging.iMSI.digits,
 					   bssap.pdu.bssmap.paging.tMSI.tmsiOctets);
-		if (isvalue(client)) {
+		if (client != null) {
 			log("CommonBssmapUnitdataCallback: IMSI/TMSI found in table, dispatching to ",
 				client);
 			CLIENT.send(bssap) to client;