diff --git a/nixos/modules/security/pam.nix b/nixos/modules/security/pam.nix
index 60a309c62028..6cde0c5527ad 100644
--- a/nixos/modules/security/pam.nix
+++ b/nixos/modules/security/pam.nix
@@ -1219,7 +1219,10 @@ in
           be changed using {option}`security.pam.u2f.authFile` option.
 
           File format is:
-          `username:first_keyHandle,first_public_key: second_keyHandle,second_public_key`
+          ```
+          <username1>:<KeyHandle1>,<UserKey1>,<CoseType1>,<Options1>:<KeyHandle2>,<UserKey2>,<CoseType2>,<Options2>:...
+          <username2>:<KeyHandle1>,<UserKey1>,<CoseType1>,<Options1>:<KeyHandle2>,<UserKey2>,<CoseType2>,<Options2>:...
+          ```
           This file can be generated using {command}`pamu2fcfg` command.
 
           More information can be found [here](https://developers.yubico.com/pam-u2f/).