diff --git a/library/GSM_RR_Types.ttcn b/library/GSM_RR_Types.ttcn
index b098118..49ceae3 100644
--- a/library/GSM_RR_Types.ttcn
+++ b/library/GSM_RR_Types.ttcn
@@ -756,7 +756,7 @@
 					 template TimingAdvance ta := ?,
 					 template ChannelDescription ch_desc := ?,
 					 template MobileAllocation ma := ?) := {
-		header := t_RrHeader(IMMEDIATE_ASSIGNMENT, 0),
+		header := t_RrHeader(IMMEDIATE_ASSIGNMENT, ?),
 		payload := {
 			imm_ass := {
 				ded_or_tbf := {