diff --git a/python_module/CMakeLists.txt b/python_module/CMakeLists.txt
index 28b0d1f9..4d605932 100644
--- a/python_module/CMakeLists.txt
+++ b/python_module/CMakeLists.txt
@@ -63,8 +63,10 @@ endif()
 
 include(UseSWIG)
 set_property(SOURCE ${SWIG_SRC} PROPERTY CPLUSPLUS ON)
+
 # cmake < 3.12 do not honor INCLUDE_DIRECTORIES property, just add include directory into SWIG_FLAGS
-set_property(SOURCE ${SWIG_SRC} PROPERTY SWIG_FLAGS ${MGB_DEF} -I${PROJECT_SOURCE_DIR}/src/serialization/include)
+# Add -I${PROJECT_BINARY_DIR}/genfiles in order to include megbrain_build_config.h so that we don't need to pass cmake flags by -D.
+set_property(SOURCE ${SWIG_SRC} PROPERTY SWIG_FLAGS -I${PROJECT_SOURCE_DIR}/src/serialization/include -I${PROJECT_BINARY_DIR}/genfiles)
 
 set(SWIG_OUTFILE_DIR ${CMAKE_CURRENT_BINARY_DIR})
 set(CMAKE_SWIG_OUTDIR ${CMAKE_CURRENT_BINARY_DIR}/megengine/_internal)
diff --git a/python_module/src/swig/mgb.i b/python_module/src/swig/mgb.i
index ff46a699..1a838f5a 100644
--- a/python_module/src/swig/mgb.i
+++ b/python_module/src/swig/mgb.i
@@ -49,6 +49,7 @@ intb4 = _mgb.intb4
 #include "plugin.h"
 %}
 
+%include "megbrain_build_config.h"
 %include "comp_node.i"
 %include "comp_graph.i"
 %include "symbol_var.i"
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 221b071a..0cafea12 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -32,10 +32,8 @@ if(MGE_WITH_CUDA AND MGE_WITH_TRT)
 endif()
 
 
-set(MGB_DEF ${MGB_DEF} PARENT_SCOPE)
 add_library(megbrain STATIC EXCLUDE_FROM_ALL ${SOURCES})
 target_link_libraries(megbrain mgb_opr_param_defs)
-target_compile_definitions(megbrain PUBLIC ${MGB_DEF})
 target_include_directories(megbrain PUBLIC ${MGB_INC})
 
 if(MGE_WITH_CUDA)