diff --git a/dist-gpw.sh b/dist-gpw.sh
index 334cfe9..f292e88 100755
--- a/dist-gpw.sh
+++ b/dist-gpw.sh
@@ -3,6 +3,13 @@
 # Create a archive 'gpw32-*.zip' (gpwYMMDD.zip) with Win32 (MinGW) build
 # of the Golded+.
 
+if [ ! $OSTYPE = "cygwin" ]
+then
+  echo "This is not Cygwin enviroment, exit."
+  exit
+fi
+
+
 date=`date +%Y%m%d`
 name=../gpw32-115-${date}.zip