diff --git a/python-ud3tn-utils/ud3tn_utils/aap2/aap2_client.py b/python-ud3tn-utils/ud3tn_utils/aap2/aap2_client.py
index 7926f70..fe988f2 100644
--- a/python-ud3tn-utils/ud3tn_utils/aap2/aap2_client.py
+++ b/python-ud3tn-utils/ud3tn_utils/aap2/aap2_client.py
@@ -9,7 +9,7 @@ import socket
 import uuid
 
 from google.protobuf.internal.decoder import _DecodeVarint32
-from google.protobuf.internal.encoder import _EncodeVarint
+from google.protobuf.internal.encoder import _VarintBytes
 
 from .generated import aap2_pb2
 
@@ -334,10 +334,8 @@ class AAP2Client(abc.ABC):
 
         """
         msg_bin = msg.SerializeToString()
-        varint_bytes = bytearray()
-        _EncodeVarint(lambda b: varint_bytes.extend(b), len(msg_bin))
-        self.socket.send(varint_bytes)
-        self.socket.send(msg_bin)
+        delimited_msg = _VarintBytes(len(msg_bin)) + msg_bin
+        self.socket.send(delimited_msg)
 
     def send_adu(self, adu_msg, bundle_data):
         """Send a bundle ADU (Protobuf with extra payload data).