diff --git a/library/RSL_Types.ttcn b/library/RSL_Types.ttcn
index acf7d40af..cad8a34e2 100644
--- a/library/RSL_Types.ttcn
+++ b/library/RSL_Types.ttcn
@@ -832,7 +832,7 @@ module RSL_Types {
 	template (value) RSL_IE_MultirateCfg ts_RSL_MultirateCfg(boolean icmi := true, uint2_t start_mode := 0,
 								 BIT8 codec_modes := '00000100'B /* 5,90k */,
 								 octetstring params := ''O) := {
-		len := 2,
+		len := 2 + lengthof(params),
 		mr_speech_ver := 1,
 		nscb := false,
 		icmi := icmi,