diff --git a/library/L1CTL_PortType.ttcn b/library/L1CTL_PortType.ttcn
index 19b3ee3..5c554c2 100644
--- a/library/L1CTL_PortType.ttcn
+++ b/library/L1CTL_PortType.ttcn
@@ -42,7 +42,10 @@
 		return len;
 	}
 
-	function f_L1CTL_FBSB(L1CTL_PT pt, Arfcn arfcn, L1ctlCcchMode ccch_mode := CCCH_MODE_COMBINED, integer rxlev_exp := 57) {
+	function f_L1CTL_FBSB(L1CTL_PT pt, GsmBandArfcn arfcn,
+			      L1ctlCcchMode ccch_mode := CCCH_MODE_COMBINED,
+			      integer rxlev_exp := 57)
+	{
 		timer T := 15.0;
 		for (var integer i := 0; i < 10; i := i+1) {
 			var L1ctlDlMessage dl;