s/fileno\(stdin\)/STDIN_FILENO/g
s/fileno\(stdout\)/STDOUT_FILENO/g
diff --git a/shell/hush.c b/shell/hush.c
index 5da9757..0a32099 100644
--- a/shell/hush.c
+++ b/shell/hush.c
@@ -2825,7 +2825,7 @@
 	 *    standard output is a terminal
 	 *    Refer to Posix.2, the description of the `sh' utility. */
 	if (argv[optind]==NULL && input==stdin &&
-			isatty(fileno(stdin)) && isatty(fileno(stdout))) {
+			isatty(STDIN_FILENO) && isatty(STDOUT_FILENO)) {
 		interactive++;
 	}