diff --git a/library/IPA_Types.ttcn b/library/IPA_Types.ttcn
index eb8081c..e951e10 100644
--- a/library/IPA_Types.ttcn
+++ b/library/IPA_Types.ttcn
@@ -40,7 +40,7 @@
 	IpaExtStreamId	streamIdExt optional,
 	octetstring	payloadData
 } with {
-	variant (lengthInd) "LENGTHTO(payloadData)";
+	variant (lengthInd) "LENGTHTO(streamIdExt,payloadData)";
 	variant (lengthInd) "FIELDLENGTH(16)";
 	variant (lengthInd) "BYTEORDER(last)";
 	variant (streamIdExt) "PRESENCE(streamId=IPAC_PROTO_OSMO)";