diff --git a/conf/fail2ban/jails.conf b/conf/fail2ban/jails.conf
index b434fc99..b0faa6f1 100644
--- a/conf/fail2ban/jails.conf
+++ b/conf/fail2ban/jails.conf
@@ -5,7 +5,7 @@
 # Whitelist our own IP addresses. 127.0.0.1/8 is the default. But our status checks
 # ping services over the public interface so we should whitelist that address of
 # ours too. The string is substituted during installation.
-ignoreip = 127.0.0.1/8 ::1/128 PUBLIC_IP PUBLIC_IPV6/64 ADMIN_HOME_IP ADMIN_HOME_IPV6/64
+ignoreip = 127.0.0.1/8 ::1/128 PUBLIC_IP PUBLIC_IPV6/64 ADMIN_HOME_IP ADMIN_HOME_IPV6
 bantime = 15m
 findtime = 120m
 maxretry = 4
diff --git a/setup/system.sh b/setup/system.sh
index 2fb92b75..e52dd049 100755
--- a/setup/system.sh
+++ b/setup/system.sh
@@ -346,10 +346,17 @@ systemctl restart systemd-resolved
 # Configure the Fail2Ban installation to prevent dumb bruce-force attacks against dovecot, postfix, ssh, etc.
 rm -f /etc/fail2ban/jail.local # we used to use this file but don't anymore
 rm -f /etc/fail2ban/jail.d/defaults-debian.conf # removes default config so we can manage all of fail2ban rules in one config
+
+if [ ! -z "$ADMIN_HOME_IPV6" ]; then
+    ADMIN_HOME_IPV6_FB="${ADMIN_HOME_IPV6}/64"
+else
+	ADMIN_HOME_IPV6_FB=""
+fi
+
 cat conf/fail2ban/jails.conf \
 	| sed "s/PUBLIC_IPV6/$PUBLIC_IPV6/g" \
 	| sed "s/PUBLIC_IP/$PUBLIC_IP/g" \
-	| sed "s/ADMIN_HOME_IPV6/$ADMIN_HOME_IPV6/g" \
+	| sed "s/ADMIN_HOME_IPV6/$ADMIN_HOME_IPV6_FB/g" \
 	| sed "s/ADMIN_HOME_IP/$ADMIN_HOME_IP/g" \
 	| sed "s#STORAGE_ROOT#$STORAGE_ROOT#" \
 	> /etc/fail2ban/jail.d/00-mailinabox.conf