diff --git a/compose.yaml b/compose.yaml
index 1567b54..3e5422e 100644
--- a/compose.yaml
+++ b/compose.yaml
@@ -11,7 +11,7 @@ services:
     cap_add:
       - NET_ADMIN
     environment:
-      - MTU=1250
+      - TUN-MTU=1250
       - VPN_SERVICE_PROVIDER=${VPN_SERVICE_PROVIDER}
       - OPENVPN_USER=${OPENVPN_USER}
       - OPENVPN_PASSWORD=${OPENVPN_PASSWORD}