diff --git a/contrib/sni-router/mtg-config.toml b/contrib/sni-router/mtg-config.toml
index c45046a2c..855904863 100644
--- a/contrib/sni-router/mtg-config.toml
+++ b/contrib/sni-router/mtg-config.toml
@@ -5,7 +5,7 @@
 # 3. Replace example.com with your actual domain everywhere.
 
 secret = "PASTE_YOUR_SECRET_HERE"
-bind-to = "0.0.0.0:3128"
+bind-to = "[::]:3128"
 
 # HAProxy in front sends PROXY protocol v2 headers so mtg can see the
 # real client IP.  Keep this in sync with haproxy.cfg (`send-proxy-v2`).