diff --git a/nixos/modules/services/networking/pppd.nix b/nixos/modules/services/networking/pppd.nix
index db135911764..e96c27bd84b 100644
--- a/nixos/modules/services/networking/pppd.nix
+++ b/nixos/modules/services/networking/pppd.nix
@@ -23,6 +23,7 @@ in
 
       peers = mkOption {
         default = {};
+        description = "pppd peers.";
         type = types.attrsOf (types.submodule (
           { name, ... }:
           {