diff --git a/nixos/modules/security/pam.nix b/nixos/modules/security/pam.nix
index 814dd21b53d..f9aa4136c8d 100644
--- a/nixos/modules/security/pam.nix
+++ b/nixos/modules/security/pam.nix
@@ -386,8 +386,7 @@ in
 
     security.pam.services = mkOption {
       default = [];
-      type = types.loaOf types.optionSet;
-      options = [ pamOpts ];
+      type = with types; loaOf (submodule pamOpts);
       description =
         ''
           This option defines the PAM services.  A service typically