diff --git a/README.markdown b/README.markdown
index 3902c83..0faa262 100644
--- a/README.markdown
+++ b/README.markdown
@@ -159,5 +159,11 @@ Building for Windows
 
     make -f Makefile.mingw32
 
-Compiling cctl-prog with cygwin's GCC may not work.
+The Linux/OSX version of `cctl-prog` compiles and runs under cygwin.
+
+Run the createdevices.sh script in cygwin to populate /dev.
+
+In cygwin COM ports are available as /dev/ttySX.
+BEWARE, THEY ARE NUMBERED FROM 0
+ie. COM7 = /dev/ttyS6