diff --git a/hosts/carbon/ppp.nix b/hosts/carbon/ppp.nix
index 8a22cf6..784c1de 100644
--- a/hosts/carbon/ppp.nix
+++ b/hosts/carbon/ppp.nix
@@ -54,7 +54,7 @@
   };
 
   clerie.firewall.extraForwardMangleCommands = ''
-    ip46tables -t mangle -A forward-mangle -p tcp -m tcp --tcp-flags SYN,RST SYN -j TCPMSS --set-mss 1416
+    ip46tables -t mangle -A forward-mangle -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp-mss-to-pmtu
   '';
 
 }