From 2e929c9e5abdab762687fd1c0034a3a0246eb050 Mon Sep 17 00:00:00 2001
From: Tom Early <n7tae@tearly.net>
Date: Sun, 11 Aug 2019 06:22:54 -0700
Subject: [PATCH] fix GetLetter

---
 qndtmf.sh | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/qndtmf.sh b/qndtmf.sh
index 5db5b4a..176501a 100755
--- a/qndtmf.sh
+++ b/qndtmf.sh
@@ -18,9 +18,11 @@
 # We set this to spaces, it will be set later
 
 GetLetter () {
+	local i
 	if [[ $1 == +([0-9]) ]]; then
-		if [ $1 -gt 0 ] && [ $1 -le 26 ]; then
-			LETTER=${LETTERS[$1-1]}
+		i=`expr $1 - 1`
+		if [ $i -ge 0 ] && [ $i -lt 26 ]; then
+			LETTER=${LETTERS[$i]}
 			return
 		fi
 	fi