/* Some System V have job control but not sigsetmask(). */
#if !defined (HAVE_SIGSETMASK)
-#define HAVE_SIGSETMASK !defined (USG)
+#if !defined (USG)
+#define HAVE_SIGSETMASK 1
+#else
+#define HAVE_SIGSETMASK 0
+#endif
#endif
#if 0 == (HAVE_SIGSETMASK)