diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7fba034d833e484601ce1e7b08248cac399aa0fc..7ec949c3919231541d26dc2d2df423ec72b505ec 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -5,6 +5,9 @@
 
 cmake_minimum_required(VERSION 2.8 FATAL_ERROR)
 
+# do not warn about non-definition of WIN32 on cygwin
+set(CMAKE_LEGACY_CYGWIN_WIN32 0) 
+
 # if CMAKE_BUILD_TYPE is specified use it; otherwise set the default
 # build type to "RelWithDebInfo" ("-O2 -g" with gcc) prior to calling
 # project()