#define required_argument 1
#define optional_argument 2
-#if defined (__GNU_LIBRARY__) || defined (__cplusplus)
+#if defined (__GNU_LIBRARY__) || defined (__cplusplus) || defined (CYGWIN)
/* Many other libraries have conflicting prototypes for getopt, with
differences in the consts, in stdlib.h. To avoid compilation
errors, only prototype getopt for the GNU C library. */