diff --git a/regress/tty-keys.sh b/regress/tty-keys.sh
index 1b300b995..19b1623dd 100644
--- a/regress/tty-keys.sh
+++ b/regress/tty-keys.sh
@@ -21,7 +21,7 @@ exit_status=0
 format_string () {
 	case $1 in
 		*\')
-			printf '"%%%%"'
+			printf '"%%%%%%"'
 			;;
 		*)
 			printf "'%%%%'"