diff --git a/CMakeLists.txt b/CMakeLists.txt
index 5bb163bfc22ba2ce4ccf54d4fe578920fef1a49f..9274059b54239277b714e43ea47f421a60e3c05d 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -901,7 +901,7 @@ if(HAVE_SOLVER)
     if(HAVE_METIS)
       add_subdirectory(contrib/taucs)
       include_directories(contrib/taucs/src contrib/taucs/config)
-      if(WIN32)
+      if(WIN32 OR CYGWIN)
         add_definitions(-DOSTYPE_win32)
       elseif(APPLE)
         add_definitions(-DOSTYPE_darwin)