diff --git a/acme-downloader.sh b/acme-downloader.sh
index b804f189ef3c0d7ddf88f2dfe6d2578c26a5d00a..b543c1767446a00cfdb6675fc5f89ab40600c1b6 100755
--- a/acme-downloader.sh
+++ b/acme-downloader.sh
@@ -16,7 +16,7 @@ TMP_FULLCHAIN=$(mktemp)
 TMP_CA=$(mktemp)
 TMP_KEY=$(mktemp)
 
-stty -echoctl # hide ^C
+tty -s && stty -echoctl # hide ^C
 
 # function called by trap
 clean_up() {