--- gforth/envos.fs.in	2008/08/09 21:26:21	1.9
+++ gforth/envos.fs.in	2008/09/18 15:47:04	1.10
@@ -34,6 +34,11 @@ set-current
 \G invocation string of the C compiler used for libtool
     s" @CC@" ;
 
+: libtool-flags ( -- c-addr u ) \ gforth
+\G force no undefined for cygwin
+    [ s" @host_os@" s" cygwin" str= ] [IF]  s"  -no-undefined "
+    [ELSE]  s" "  [THEN] ;
+
 \ test for the presence of libffi or ffcall
 @FFCALLFLAG@ constant ffcall-present \ libffi present (on building)
 @LIBFFIFLAG@ constant libffi-present \ ffcall libs present (on building)