#2890: support os.O_ASYNC and fcntl.FASYNC.
diff --git a/Modules/fcntlmodule.c b/Modules/fcntlmodule.c
index 96a6cc8..0c85f47 100644
--- a/Modules/fcntlmodule.c
+++ b/Modules/fcntlmodule.c
@@ -510,6 +510,9 @@
         if (ins(d, "F_SETLKW64", (long)F_SETLKW64)) return -1;
 #endif
 /* GNU extensions, as of glibc 2.2.4. */
+#ifdef FASYNC
+        if (ins(d, "FASYNC", (long)FASYNC)) return -1;
+#endif
 #ifdef F_SETLEASE
         if (ins(d, "F_SETLEASE", (long)F_SETLEASE)) return -1;
 #endif