diff --git a/sysinfo/GSM_SystemInformation.ttcn b/sysinfo/GSM_SystemInformation.ttcn
index 552463f..8413ee3 100644
--- a/sysinfo/GSM_SystemInformation.ttcn
+++ b/sysinfo/GSM_SystemInformation.ttcn
@@ -6,6 +6,7 @@
 module GSM_SystemInformation {
 
 	import from General_Types all;
+	import from GSM_Types all;
 	import from Osmocom_Types all;
 
 	type record L2PseudoLength {
@@ -32,10 +33,10 @@
 		L2PseudoLength	l2_plen,
 		uint4_t		skip_indicator,
 		uint4_t		rr_protocol_discriminator,
-		OCT1		message_type
+		RrMessageType	message_type
 	} with { variant "" };
 
-	template SystemInformationHeader t_SiHeader(OCT1 msg_type, uint6_t len) := {
+	template SystemInformationHeader t_SiHeader(RrMessageType msg_type, uint6_t len) := {
 		l2_plen := t_L2Pseudolength(len),
 		rr_protocol_discriminator := 6,
 		message_type := msg_type
@@ -234,16 +235,16 @@
 		SystemInformationType5bis	si5bis,
 		SystemInformationType5ter	si5ter,
 		SystemInformationType6		si6
-	} with { variant "TAG(si1, header.message_type = '19'O;
-			      si2, header.message_type = '1A'O;
-			      si2bis, header.message_type = '02'O;
-			      si2ter, header.message_type = '03'O;
-			      si3, header.message_type = '1B'O;
-			      si4, header.message_type = '1C'O;
-			      si5, header.message_type = '1D'O;
-			      si5bis, header.message_type = '05'O;
-			      si5ter, header.message_type = '06'O;
-			      si6, header.message_type = '1E'O;
+	} with { variant "TAG(si1, header.message_type = SYSTEM_INFORMATION_TYPE_1;
+			      si2, header.message_type = SYSTEM_INFORMATION_TYPE_2;
+			      si2bis, header.message_type = SYSTEM_INFORMATION_TYPE_2bis;
+			      si2ter, header.message_type = SYSTEM_INFORMATION_TYPE_2ter;
+			      si3, header.message_type = SYSTEM_INFORMATION_TYPE_3;
+			      si4, header.message_type = SYSTEM_INFORMATION_TYPE_4;
+			      si5, header.message_type = SYSTEM_INFORMATION_TYPE_5;
+			      si5bis, header.message_type = SYSTEM_INFORMATION_TYPE_5bis;
+			      si5ter, header.message_type = SYSTEM_INFORMATION_TYPE_5ter;
+			      si6, header.message_type = SYSTEM_INFORMATION_TYPE_6;
 			)" };
 
 	external function enc_SystemInformation(in SystemInformation si) return octetstring