diff --git a/nixos/modules/services/databases/ferretdb.nix b/nixos/modules/services/databases/ferretdb.nix
index a7e3fa81c48f..21754b3d1bbc 100644
--- a/nixos/modules/services/databases/ferretdb.nix
+++ b/nixos/modules/services/databases/ferretdb.nix
@@ -19,8 +19,22 @@ in
       };
 
       settings = lib.mkOption {
-        type =
-          lib.types.submodule { freeformType = with lib.types; attrsOf str; };
+        type = lib.types.submodule {
+          freeformType = with lib.types; attrsOf str;
+          options = {
+            FERRETDB_HANDLER  = lib.mkOption {
+              type = lib.types.enum [ "sqlite" "pg" ];
+              default = "sqlite";
+              description = "Backend handler";
+            };
+
+            FERRETDB_SQLITE_URL = lib.mkOption {
+              type = lib.types.str;
+              default = "file:/var/lib/ferretdb/";
+              description = "SQLite URI (directory) for 'sqlite' handler";
+            };
+          };
+        };
         example = {
           FERRETDB_LOG_LEVEL = "warn";
           FERRETDB_MODE = "normal";
@@ -36,11 +50,7 @@ in
 
   config = lib.mkIf cfg.enable
     {
-
-      services.ferretdb.settings = {
-        FERRETDB_HANDLER = lib.mkDefault "sqlite";
-        FERRETDB_SQLITE_URL = lib.mkDefault "file:/var/lib/ferretdb/";
-      };
+      services.ferretdb.settings = { };
 
       systemd.services.ferretdb = {
         description = "FerretDB";