diff --git a/CMakeLists.txt b/CMakeLists.txt
index d0343d3ba77ec67de23a928cb8dbcd1fd84a5994..92331d97952e41004066f958b80929ddc4b3e18c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -41,7 +41,7 @@ SET( GRIDDIM
 	"GRIDDIM" )
 
 CONFIGURE_FILE( ${CMAKE_CURRENT_SOURCE_DIR}/cmake/cmake_config.h.in ${CMAKE_CURRENT_BINARY_DIR}/cmake_config.h )
-ADD_CXX_FLAGS( ${CUSTOM_FLAGS} )
+ADD_DEFINITIONS( ${CUSTOM_FLAGS} )
 
 ADD_DUNE_MODULES( stuff common istl grid fem geometry localfunctions)