1 files changed, 1 insertions, 1 deletions
diff --git a/main.c b/main.c
index b1773d25..b60692a3 100644
--- a/main.c
+++ b/main.c
@@ -621,7 +621,7 @@ out:
 #ifdef GAWKDEBUG
 	setbuf(stdout, (char *) NULL);	/* make debugging easier */
 #endif
-	if (ISATTY(fileno(stdout)))
+	if (os_isatty(fileno(stdout)))
 		output_is_tty = TRUE;
 	/* No -f or --source options, use next arg */
 	if (srcfiles->next == srcfiles) {