diff --git a/CMakeLists.txt b/CMakeLists.txt
index a826de9..0e8b247 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,6 +2,8 @@ cmake_minimum_required(VERSION 3.03)
 
 project(ets_logout VERSION 0.1)
 
+add_subdirectory(tcpip_rs232)
+
 add_library(
   ets_logout
   src/ets_logout.cxx