diff --git a/src/python/python3/CMakeLists.txt b/src/python/python3/CMakeLists.txt
index 03894cf..c8de846 100644
--- a/src/python/python3/CMakeLists.txt
+++ b/src/python/python3/CMakeLists.txt
@@ -25,7 +25,7 @@ endif ()
 
 set_target_properties (${SWIG_MODULE_python3-mraa_REAL_NAME} PROPERTIES
   OUTPUT_NAME _mraa
-  COMPILE_FLAGS "${CMAKE_C_FLAGS} -DSWIGPYTHON=${SWIG_FOUND} -DSWIGPYTHON3=${SWIG_FOUND}"
+  COMPILE_FLAGS "-DSWIGPYTHON=${SWIG_FOUND} -DSWIGPYTHON3=${SWIG_FOUND}"
 )
 
 install (TARGETS ${SWIG_MODULE_python3-mraa_REAL_NAME}