--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -72,7 +72,7 @@ if (NOT MSVC)
       set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -fsanitize=address -fno-omit-frame-pointer -fsanitize=undefined")
    endif()
 
-   set(CMAKE_CXX_FLAGS -std=c++11)
+   set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
    set(GCC_COMPILE_FLAGS "-fvisibility=hidden -fPIC -fno-strict-aliasing -D_LARGEFILE64_SOURCE=1 -D_FILE_OFFSET_BITS=64 -Wall -Wextra -Wno-unused-local-typedefs -Wno-unused-value -Wno-unused-parameter -Wno-unused-variable")
 
    if (NOT BUILD_X64)