diff --git a/lib/pleroma/web/activity_pub/object_validators/types/recipients.ex b/lib/pleroma/web/activity_pub/object_validators/types/recipients.ex
new file mode 100644
index 000000000..48fe61e1a
--- /dev/null
+++ b/lib/pleroma/web/activity_pub/object_validators/types/recipients.ex
@@ -0,0 +1,34 @@
+defmodule Pleroma.Web.ActivityPub.ObjectValidators.Types.Recipients do
+  use Ecto.Type
+
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types.ObjectID
+
+  def type, do: {:array, ObjectID}
+
+  def cast(object) when is_binary(object) do
+    cast([object])
+  end
+
+  def cast(data) when is_list(data) do
+    data
+    |> Enum.reduce({:ok, []}, fn element, acc ->
+      case {acc, ObjectID.cast(element)} do
+        {:error, _} -> :error
+        {_, :error} -> :error
+        {{:ok, list}, {:ok, id}} -> {:ok, [id | list]}
+      end
+    end)
+  end
+
+  def cast(_) do
+    :error
+  end
+
+  def dump(data) do
+    {:ok, data}
+  end
+
+  def load(data) do
+    {:ok, data}
+  end
+end
diff --git a/test/web/activity_pub/object_validators/types/recipients_test.exs b/test/web/activity_pub/object_validators/types/recipients_test.exs
new file mode 100644
index 000000000..f278f039b
--- /dev/null
+++ b/test/web/activity_pub/object_validators/types/recipients_test.exs
@@ -0,0 +1,27 @@
+defmodule Pleroma.Web.ObjectValidators.Types.RecipientsTest do
+  alias Pleroma.Web.ActivityPub.ObjectValidators.Types.Recipients
+  use Pleroma.DataCase
+
+  test "it asserts that all elements of the list are object ids" do
+    list = ["https://lain.com/users/lain", "invalid"]
+
+    assert :error == Recipients.cast(list)
+  end
+
+  test "it works with a list" do
+    list = ["https://lain.com/users/lain"]
+    assert {:ok, list} == Recipients.cast(list)
+  end
+
+  test "it works with a list with whole objects" do
+    list = ["https://lain.com/users/lain", %{"id" => "https://gensokyo.2hu/users/raymoo"}]
+    resulting_list = ["https://gensokyo.2hu/users/raymoo", "https://lain.com/users/lain"]
+    assert {:ok, resulting_list} == Recipients.cast(list)
+  end
+
+  test "it turns a single string into a list" do
+    recipient = "https://lain.com/users/lain"
+
+    assert {:ok, [recipient]} == Recipients.cast(recipient)
+  end
+end