diff --git a/compiler/cpp/CMakeLists.txt b/compiler/cpp/CMakeLists.txt
index e618877..0df790e 100644
--- a/compiler/cpp/CMakeLists.txt
+++ b/compiler/cpp/CMakeLists.txt
@@ -113,7 +113,7 @@
 # we also add the current binary directory for generated files
 include_directories(${CMAKE_CURRENT_BINARY_DIR} src)
 
-if(NOT ${WITH_PLUGIN})
+if(NOT DEFINED WITH_PLUGIN OR NOT ${WITH_PLUGIN})
     list(APPEND thrift-compiler_SOURCES ${compiler_core})
 endif()