diff --git a/usr.bin/script/script.c b/usr.bin/script/script.c
index ad706dcdd350..bd2de283ebf8 100644
--- a/usr.bin/script/script.c
+++ b/usr.bin/script/script.c
@@ -126,7 +126,7 @@ main(int argc, char *argv[])
 	if ((fscript = fopen(fname, aflg ? "a" : "w")) == NULL)
 		err(1, "%s", fname);
 
-	if (ttyflg = isatty(STDIN_FILENO)) {
+	if ((ttyflg = isatty(STDIN_FILENO)) != 0) {
 		if (tcgetattr(STDIN_FILENO, &tt) == -1)
 			err(1, "tcgetattr");
 		if (ioctl(STDIN_FILENO, TIOCGWINSZ, &win) == -1)