diff --git a/pcu/GPRS_Components.ttcn b/pcu/GPRS_Components.ttcn
index 3658fc8..830f8d3 100644
--- a/pcu/GPRS_Components.ttcn
+++ b/pcu/GPRS_Components.ttcn
@@ -1153,7 +1153,7 @@
 }
 
 /* Return true if a given Packet Paging Request contains the given IMSI, false otherwise */
-function f_pkt_paging_match_imsi(in PacketPagingReq req, template hexstring imsi,
+function f_pkt_paging_match_imsi(in PacketPagingReq req, template (present) hexstring imsi,
 				 boolean cs_domain := true, boolean ps_domain := true)
 runs on MS_BTS_IFACE_CT return boolean {
 	if (not ispresent(req.repeated_pageinfo)) {