diff --git a/examples/ClientTests/CMakeLists.txt b/examples/ClientTests/CMakeLists.txt
index 1e9055b0e24c20314f2c36b7431650a4c15b32da..6da564919219cb06acdf057b2c7ce398c342fb15 100644
--- a/examples/ClientTests/CMakeLists.txt
+++ b/examples/ClientTests/CMakeLists.txt
@@ -19,7 +19,9 @@ dd4hep_package (ClientTests MAJOR 0 MINOR 0 PATCH 1
   OPTIONAL     XERCESC
   INCLUDE_DIRS include )
 #--------------------------------------------------------------------------
-dd4hep_add_plugin( ClientTests SOURCES src/*.cpp  )
+dd4hep_add_plugin( ClientTests SOURCES src/*.cpp
+  OPTIONAL       [BOOST SOURCES src_boost/*.cpp]
+  )
 dd4hep_install_dir( compact scripts DESTINATION ${DD4hep_DIR}/examples/ClientTests )
 #--------------------------------------------------------------------------
 
diff --git a/examples/ClientTests/src/JsonTest.cpp b/examples/ClientTests/src_boost/JsonTest.cpp
similarity index 100%
rename from examples/ClientTests/src/JsonTest.cpp
rename to examples/ClientTests/src_boost/JsonTest.cpp