diff --git a/lib/mobilizon/instances/instance_actor.ex b/lib/mobilizon/instances/instance_actor.ex
index 376498ad9..a3016995a 100644
--- a/lib/mobilizon/instances/instance_actor.ex
+++ b/lib/mobilizon/instances/instance_actor.ex
@@ -34,6 +34,10 @@ defmodule Mobilizon.Instances.InstanceActor do
     instance_actor
     |> cast(attrs, @attrs)
     |> validate_required(@required_attrs)
+    |> validate_length(:domain, max: 254)
+    |> validate_length(:instance_name, max: 254)
+    |> validate_length(:software, max: 254)
+    |> validate_length(:software_version, max: 254)
     |> unique_constraint(:domain)
   end
 end
diff --git a/priv/repo/migrations/20240104103036_change_actor_instance_description_type_to_text.exs b/priv/repo/migrations/20240104103036_change_actor_instance_description_type_to_text.exs
new file mode 100644
index 000000000..9db48a9a2
--- /dev/null
+++ b/priv/repo/migrations/20240104103036_change_actor_instance_description_type_to_text.exs
@@ -0,0 +1,15 @@
+defmodule Mobilizon.Storage.Repo.Migrations.ChangeActorInstanceDescriptionTypeToText do
+  use Ecto.Migration
+
+  def up do
+    alter table(:instance_actors) do
+      modify(:instance_description, :text)
+    end
+  end
+
+  def down do
+    alter table(:instance_actors) do
+      modify(:instance_description, :string)
+    end
+  end
+end