diff --git a/nix/lib/dns.nix b/nix/lib/dns.nix
index 1e8f4b4..20a31ec 100644
--- a/nix/lib/dns.nix
+++ b/nix/lib/dns.nix
@@ -23,7 +23,7 @@ rec {
   localZones =
     let
       # ip6.arpa aggregation size in CIDR bits
-      reverseZone6Size = 60;
+      reverseZone6Size = 56;
 
       hosts4Records = hosts4:
         builtins.attrValues (