diff --git a/config/config.exs b/config/config.exs
index d8bf921bb..1dc196a6b 100644
--- a/config/config.exs
+++ b/config/config.exs
@@ -238,6 +238,7 @@ config :pleroma, :instance,
   max_remote_account_fields: 20,
   account_field_name_length: 512,
   account_field_value_length: 2048,
+  registration_reason_length: 500,
   external_user_synchronization: true,
   extended_nickname_format: true,
   cleanup_attachments: false,
diff --git a/lib/pleroma/user.ex b/lib/pleroma/user.ex
index a78123fe4..913b6afd1 100644
--- a/lib/pleroma/user.ex
+++ b/lib/pleroma/user.ex
@@ -641,6 +641,7 @@ defmodule Pleroma.User do
   def register_changeset(struct, params \\ %{}, opts \\ []) do
     bio_limit = Config.get([:instance, :user_bio_length], 5000)
     name_limit = Config.get([:instance, :user_name_length], 100)
+    reason_limit = Config.get([:instance, :registration_reason_length], 500)
     params = Map.put_new(params, :accepts_chat_messages, true)
 
     need_confirmation? =
@@ -681,6 +682,7 @@ defmodule Pleroma.User do
     |> validate_format(:email, @email_regex)
     |> validate_length(:bio, max: bio_limit)
     |> validate_length(:name, min: 1, max: name_limit)
+    |> validate_length(:registration_reason, max: reason_limit)
     |> maybe_validate_required_email(opts[:external])
     |> put_password_hash
     |> put_ap_id()
diff --git a/priv/repo/migrations/20200712234852_add_approval_fields_to_users.exs b/priv/repo/migrations/20200712234852_add_approval_fields_to_users.exs
index 559640f01..43f741a5b 100644
--- a/priv/repo/migrations/20200712234852_add_approval_fields_to_users.exs
+++ b/priv/repo/migrations/20200712234852_add_approval_fields_to_users.exs
@@ -4,7 +4,7 @@ defmodule Pleroma.Repo.Migrations.AddApprovalFieldsToUsers do
   def change do
     alter table(:users) do
       add(:approval_pending, :boolean)
-      add(:registration_reason, :string)
+      add(:registration_reason, :text)
     end
   end
 end
diff --git a/test/user_test.exs b/test/user_test.exs
index 5da86bcec..5bf677666 100644
--- a/test/user_test.exs
+++ b/test/user_test.exs
@@ -550,7 +550,8 @@ defmodule Pleroma.UserTest do
       nickname: "nick",
       password: "test",
       password_confirmation: "test",
-      email: "email@example.com"
+      email: "email@example.com",
+      registration_reason: "I'm a cool guy :)"
     }
     setup do: clear_config([:instance, :account_approval_required], true)
 
@@ -561,6 +562,21 @@ defmodule Pleroma.UserTest do
       {:ok, user} = Repo.insert(changeset)
 
       assert user.approval_pending
+      assert user.registration_reason == "I'm a cool guy :)"
+    end
+
+    test "it restricts length of registration reason" do
+      reason_limit = Pleroma.Config.get([:instance, :registration_reason_length])
+
+      assert is_integer(reason_limit)
+
+      params =
+        @full_user_data
+        |> Map.put(:registration_reason, "Quia et nesciunt dolores numquam ipsam nisi sapiente soluta. Ullam repudiandae nisi quam porro officiis officiis ad. Consequatur animi velit ex quia. Odit voluptatem perferendis quia ut nisi. Dignissimos sit soluta atque aliquid dolorem ut dolorum ut. Labore voluptates iste iusto amet voluptatum earum. Ad fugit illum nam eos ut nemo. Pariatur ea fuga non aspernatur. Dignissimos debitis officia corporis est nisi ab et. Atque itaque alias eius voluptas minus. Accusamus numquam tempore occaecati in.")
+
+      changeset = User.register_changeset(%User{}, params)
+
+      refute changeset.valid?
     end
   end