diff --git a/library/L3_Templates.ttcn b/library/L3_Templates.ttcn
index f072f78..8c0f494 100644
--- a/library/L3_Templates.ttcn
+++ b/library/L3_Templates.ttcn
@@ -117,7 +117,7 @@
 		return f_enc_IMSI_L3(valueof(digits))
 	}
 }
-template MobileIdentityV tr_MI_IMSI(template hexstring imsi) := {
+template MobileIdentityV tr_MI_IMSI(template (present) hexstring imsi) := {
 	typeOfIdentity := '001'B,
 	oddEvenInd_identity := {
 		imsi := f_tr_MI_IMSI(imsi)