diff --git a/.cmake/Modules/Properties.cmake b/.cmake/Modules/Properties.cmake
index 107a5f8..319fb30 100644
--- a/.cmake/Modules/Properties.cmake
+++ b/.cmake/Modules/Properties.cmake
@@ -21,14 +21,17 @@ set (CMAKE_CXX_FLAGS_DEFAULT "${CMAKE_CXX_FLAGS}")
 if (MSVC)
   set (CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} /SAFESEH:NO")
   add_definitions (-D_CRT_SECURE_NO_WARNINGS=1)
+  add_definitions (-DVC_EXTRALEAN)
+  add_definitions (-DWIN32_LEAN_AND_MEAN)
+  add_definitions (-D_WIN32_WINNT=0x600)
 else ()
   if (WIN32)
     set (CMAKE_SHARED_LINKER_FLAGS "${CMAKE_SHARED_LINKER_FLAGS} -Wl,-no-undefined")
   endif ()
 
-  set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Werror -g -std=gnu99 -fvisibility=hidden")
+  set (CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -std=gnu99 -fvisibility=hidden")
   if (CMAKE_CXX_COMPILER_WORKS)
-    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Werror -g ${CXX11_FLAG} -fvisibility=hidden")
+    set (CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra ${CXX11_FLAG} -fvisibility=hidden")
   endif ()
 endif ()
 
diff --git a/src/compat/internal.h b/src/compat/internal.h
index b2f6e80..acfb568 100644
--- a/src/compat/internal.h
+++ b/src/compat/internal.h
@@ -25,10 +25,6 @@
 # define INTERNAL_H_
 
 # if defined(_WIN32) && !defined(__CYGWIN__)
-#  define VC_EXTRALEAN
-#  define WIN32_LEAN_AND_MEAN
-#  undef _WIN32_WINNT
-#  define _WIN32_WINNT 0x0600
 #  include <windows.h>
 
 #  if defined(MINGW_DEFINE_OFF_T) && (defined(__MINGW32__) || defined(__MINGW64__))