--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -252,15 +252,6 @@ set(AVX2_OPT OFF)
 set(FMA_OPT OFF)
 set(SSE41_OPT OFF)
 set(MARCH_NATIVE_OPT OFF)
-foreach(flag ${_enable_vector_unit_list})  # from OptimizeForArchitecture()
-    string(TOUPPER "${flag}" flag)
-    string(REPLACE "\." "_" flag "${flag}")
-    set(simd_flags "${simd_flags} -D${flag}")
-    string(REPLACE "_" "" flag "${flag}")
-    if("${flag}" MATCHES "AVX|AVX2|FMA|SSE41")
-        set("${flag}_OPT" ON)
-    endif()
-endforeach(flag)
 if (NOT MSVC)
    set(MARCH_NATIVE_FLAGS "${MARCH_NATIVE_FLAGS} -O3 -ffast-math")
 endif()
