diff --git a/openvpn-install.sh b/openvpn-install.sh
index 8eaae90..2f9972f 100755
--- a/openvpn-install.sh
+++ b/openvpn-install.sh
@@ -1138,12 +1138,13 @@ function revokeClient() {
 	echo ""
 	echo "Select the existing client certificate you want to revoke"
 	tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | grep "^V" | cut -d '=' -f 2 | nl -s ') '
-	if [[ $NUMBEROFCLIENTS == '1' ]]; then
-		read -rp "Select one client [1]: " CLIENTNUMBER
-	else
-		read -rp "Select one client [1-$NUMBEROFCLIENTS]: " CLIENTNUMBER
-	fi
-
+	until [[ $CLIENTNUMBER -ge 1 && $CLIENTNUMBER -le $NUMBEROFCLIENTS ]]; do
+		if [[ $CLIENTNUMBER == '1' ]]; then
+			read -rp "Select one client [1]: " CLIENTNUMBER
+		else
+			read -rp "Select one client [1-$NUMBEROFCLIENTS]: " CLIENTNUMBER
+		fi
+	done
 	CLIENT=$(tail -n +2 /etc/openvpn/easy-rsa/pki/index.txt | grep "^V" | cut -d '=' -f 2 | sed -n "$CLIENTNUMBER"p)
 	cd /etc/openvpn/easy-rsa/ || return
 	./easyrsa --batch revoke "$CLIENT"