diff --git a/libshviotqt/tests/serialportsocket/mockrpcconnection.cpp b/libshviotqt/tests/serialportsocket/mockrpcconnection.cpp
index 40c137e4c..bf1eab2b2 100644
--- a/libshviotqt/tests/serialportsocket/mockrpcconnection.cpp
+++ b/libshviotqt/tests/serialportsocket/mockrpcconnection.cpp
@@ -5,6 +5,7 @@
 MockRpcConnection::MockRpcConnection(QObject *parent)
 	: shv::iotqt::rpc::SocketRpcConnection{parent}
 {
+	setClientProtocolType(shv::chainpack::Rpc::ProtocolType::ChainPack);
 }
 
 void MockRpcConnection::close()