diff --git a/library/M3UA_CodecPort_CtrlFunct.ttcn b/library/M3UA_CodecPort_CtrlFunct.ttcn
index fc38e43..6f06e2c 100644
--- a/library/M3UA_CodecPort_CtrlFunct.ttcn
+++ b/library/M3UA_CodecPort_CtrlFunct.ttcn
@@ -40,5 +40,12 @@
     out UserData userData
   ) return Result;
 
+  external function f_IPL4_setGetMsgLen(
+    inout M3UA_CODEC_PT portRef,
+    in ConnectionId id,
+    inout f_IPL4_getMsgLen f,
+    in ro_integer msgLenArgs
+  )
+
 }