diff --git a/asterisk/IMS_ConnectionHandler.ttcn b/asterisk/IMS_ConnectionHandler.ttcn
index 3c3a51b..9f7d0f1 100644
--- a/asterisk/IMS_ConnectionHandler.ttcn
+++ b/asterisk/IMS_ConnectionHandler.ttcn
@@ -35,7 +35,7 @@
 }
 
 const integer c_def_expires := 600000; /* 3GPP TS 24.229 5.1.1.2.1 e) */
-const char c_sip_server_name := "osmo-ttcn3-hacks/0.23";
+const charstring c_sip_server_name := "osmo-ttcn3-hacks/0.23";
 
 
 type port IMSCoord_PT message