diff --git a/nixos/modules/services/mail/stalwart-mail.nix b/nixos/modules/services/mail/stalwart-mail.nix
index c69a2ca400ba..06b48c86907c 100644
--- a/nixos/modules/services/mail/stalwart-mail.nix
+++ b/nixos/modules/services/mail/stalwart-mail.nix
@@ -70,7 +70,9 @@ in {
       storage.lookup = mkDefault "db";
       storage.blob = mkDefault "blob";
       resolver.type = mkDefault "system";
-      resolver.public-suffix = mkDefault ["https://publicsuffix.org/list/public_suffix_list.dat"];
+      resolver.public-suffix = lib.mkDefault [
+        "file://${pkgs.publicsuffix-list}/share/publicsuffix/public_suffix_list.dat"
+      ];
     };
 
     systemd.services.stalwart-mail = {