diff --git a/nixos/modules/services/network-filesystems/samba.nix b/nixos/modules/services/network-filesystems/samba.nix
index 5d02eac8e9f1..ef368ddbeefd 100644
--- a/nixos/modules/services/network-filesystems/samba.nix
+++ b/nixos/modules/services/network-filesystems/samba.nix
@@ -154,7 +154,7 @@ in
       };
 
       securityType = mkOption {
-        type = types.str;
+        type = types.enum [ "auto" "user" "domain" "ads" ];
         default = "user";
         description = lib.mdDoc "Samba security type";
       };