diff --git a/lib/waffle_ecto/schema.ex b/lib/waffle_ecto/schema.ex
index b4a774e..fc360e1 100644
--- a/lib/waffle_ecto/schema.ex
+++ b/lib/waffle_ecto/schema.ex
@@ -21,7 +21,7 @@ defmodule Waffle.Ecto.Schema do
           field :avatar, MyApp.Uploaders.AvatarUploader.Type
         end
 
-        def changeset(user, params \\ :invalid) do
+        def changeset(user, params \\ %{}) do
           user
           |> cast(params, [:name])
           |> cast_attachments(params, [:avatar])
@@ -69,20 +69,20 @@ defmodule Waffle.Ecto.Schema do
           end
         end)
 
-      waffle_params =
-        case params do
-          :invalid ->
-            :invalid
-
-          %{} ->
+      case params do
+        params when is_map(params) and map_size(params) > 0 ->
+          waffle_params =
             params
             |> convert_params_to_binary()
             |> Map.take(allowed_param_keys)
             |> check_and_apply_scope(scope, options)
             |> Enum.into(%{})
-        end
 
-      Ecto.Changeset.cast(changeset_or_data, waffle_params, allowed)
+          Ecto.Changeset.cast(changeset_or_data, waffle_params, allowed)
+
+        _ ->
+          changeset_or_data
+      end
     end
   end
 
diff --git a/test/schema_test.exs b/test/schema_test.exs
index 7417dab..07035ec 100644
--- a/test/schema_test.exs
+++ b/test/schema_test.exs
@@ -45,7 +45,7 @@ defmodule WaffleTest.Ecto.Schema do
     %{__struct__: Plug.Upload, path: path, filename: Path.basename(path)}
   end
 
-  test "supports :invalid changeset" do
+  test "supports invalid empty changeset" do
     cs = TestUser.changeset(%TestUser{})
     assert cs.valid? == false
     assert cs.changes == %{}