diff --git a/CMakeLists.txt b/CMakeLists.txt
index f2c2fc5..151fb60 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,9 +18,10 @@ endif()
 
 # Activation du standard C++11 sur GCC
 if(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX)
+    include(CheckCXXCompilerFlag)
     CHECK_CXX_COMPILER_FLAG("-std=c++11" COMPILER_SUPPORTS_CXX11)
     CHECK_CXX_COMPILER_FLAG("-std=c++0x" COMPILER_SUPPORTS_CXX0X)
-    
+
     if(COMPILER_SUPPORTS_CXX11)
         set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
     elseif(COMPILER_SUPPORTS_CXX0X)