diff --git a/lib/pow/ecto/context.ex b/lib/pow/ecto/context.ex
index d9a74dc4..6122827c 100644
--- a/lib/pow/ecto/context.ex
+++ b/lib/pow/ecto/context.ex
@@ -91,10 +91,10 @@ defmodule Pow.Ecto.Context do
   """
   @spec authenticate(Config.t(), map()) :: user() | nil
   def authenticate(config, params) do
-    user_mod    = user_schema_mod(config)
-    user_id_field = Schema.user_id_field(user_mod)
-    login_value = params[Atom.to_string(user_id_field)]
-    password    = params["password"]
+    user_mod      = user_schema_mod(config)
+    user_id_field = user_mod.pow_user_id_field()
+    login_value   = params[Atom.to_string(user_id_field)]
+    password      = params["password"]
 
     config
     |> get_by([{user_id_field, login_value}])
@@ -161,7 +161,7 @@ defmodule Pow.Ecto.Context do
   end
 
   defp normalize_user_id_field_value(user_mod, clauses) do
-    user_id_field = Schema.user_id_field(user_mod)
+    user_id_field = user_mod.pow_user_id_field()
 
     Enum.map clauses, fn
       {^user_id_field, value} -> {user_id_field, Schema.normalize_user_id_field_value(value)}
diff --git a/lib/pow/ecto/schema.ex b/lib/pow/ecto/schema.ex
index 58fdc871..a25b3692 100644
--- a/lib/pow/ecto/schema.ex
+++ b/lib/pow/ecto/schema.ex
@@ -137,14 +137,14 @@ defmodule Pow.Ecto.Schema do
     end
   end
 
-  @spec user_id_field :: atom()
-  def user_id_field, do: :email
-
-  @spec user_id_field(Config.t() | Changeset.t() | map() | atom()) :: atom()
-  def user_id_field(config) when is_list(config), do: Config.get(config, :user_id_field, user_id_field())
-  def user_id_field(%Changeset{data: data}), do: user_id_field(data.__struct__)
-  def user_id_field(map) when is_map(map), do: user_id_field(map.__struct__)
-  def user_id_field(module), do: module.pow_user_id_field()
+
+  @doc """
+  Get user id field key from configuration.
+
+  Defaults to `:email`.
+  """
+  @spec user_id_field(Config.t()) :: atom()
+  def user_id_field(config \\ []), do: Config.get(config, :user_id_field, :email)
 
   @doc """
   Normalizes the user id field.
diff --git a/lib/pow/ecto/schema/changeset.ex b/lib/pow/ecto/schema/changeset.ex
index db80fc4b..cbbd98bb 100644
--- a/lib/pow/ecto/schema/changeset.ex
+++ b/lib/pow/ecto/schema/changeset.ex
@@ -33,7 +33,10 @@ defmodule Pow.Ecto.Schema.Changeset do
   """
   @spec user_id_field_changeset(Ecto.Schema.t() | Changeset.t(), map(), Config.t()) :: Changeset.t()
   def user_id_field_changeset(user_or_changeset, params, _config) do
-    user_id_field = Schema.user_id_field(user_or_changeset)
+    user_id_field = case user_or_changeset do
+      %Changeset{data: %struct{}} -> struct.pow_user_id_field()
+      %struct{}                   -> struct.pow_user_id_field()
+    end
 
     user_or_changeset
     |> Changeset.cast(params, [user_id_field])