diff --git a/app/models/account_note.rb b/app/models/account_note.rb
index bf61df923..b338bc92f 100644
--- a/app/models/account_note.rb
+++ b/app/models/account_note.rb
@@ -17,4 +17,5 @@ class AccountNote < ApplicationRecord
   belongs_to :target_account, class_name: 'Account'
 
   validates :account_id, uniqueness: { scope: :target_account_id }
+  validates :comment, length: { maximum: 2_000 }
 end
diff --git a/app/workers/move_worker.rb b/app/workers/move_worker.rb
index cc2c17d32..4a900e3b8 100644
--- a/app/workers/move_worker.rb
+++ b/app/workers/move_worker.rb
@@ -53,10 +53,16 @@ class MoveWorker
 
       new_note = AccountNote.find_by(account: note.account, target_account: @target_account)
       if new_note.nil?
-        AccountNote.create!(account: note.account, target_account: @target_account, comment: [text, note.comment].join("\n"))
+        begin
+          AccountNote.create!(account: note.account, target_account: @target_account, comment: [text, note.comment].join("\n"))
+        rescue ActiveRecord::RecordInvalid
+          AccountNote.create!(account: note.account, target_account: @target_account, comment: note.comment)
+        end
       else
         new_note.update!(comment: [text, note.comment, "\n", new_note.comment].join("\n"))
       end
+    rescue ActiveRecord::RecordInvalid
+      nil
     rescue => e
       @deferred_error = e
     end
diff --git a/spec/controllers/api/v1/accounts/notes_controller_spec.rb b/spec/controllers/api/v1/accounts/notes_controller_spec.rb
new file mode 100644
index 000000000..0a2957fed
--- /dev/null
+++ b/spec/controllers/api/v1/accounts/notes_controller_spec.rb
@@ -0,0 +1,48 @@
+require 'rails_helper'
+
+describe Api::V1::Accounts::NotesController do
+  render_views
+
+  let(:user)    { Fabricate(:user, account: Fabricate(:account, username: 'alice')) }
+  let(:token)   { Fabricate(:accessible_access_token, resource_owner_id: user.id, scopes: 'write:accounts') }
+  let(:account) { Fabricate(:account) }
+  let(:comment) { 'foo' }
+
+  before do
+    allow(controller).to receive(:doorkeeper_token) { token }
+  end
+
+  describe 'POST #create' do
+    subject do
+      post :create, params: { account_id: account.id, comment: comment }
+    end
+
+    context 'when account note has reasonable length' do
+      let(:comment) { 'foo' }
+
+      it 'returns http success' do
+        subject
+        expect(response).to have_http_status(200)
+      end
+
+      it 'updates account note' do
+        subject
+        expect(AccountNote.find_by(account_id: user.account.id, target_account_id: account.id).comment).to eq comment
+      end
+    end
+
+    context 'when account note exceends allowed length' do
+      let(:comment) { 'a' * 2_001 }
+
+      it 'returns 422' do
+        subject
+        expect(response).to have_http_status(422)
+      end
+
+      it 'does not create account note' do
+        subject
+        expect(AccountNote.where(account_id: user.account.id, target_account_id: account.id).exists?).to be_falsey
+      end
+    end
+  end
+end
diff --git a/spec/workers/move_worker_spec.rb b/spec/workers/move_worker_spec.rb
index 8ab4f182f..82449b0c7 100644
--- a/spec/workers/move_worker_spec.rb
+++ b/spec/workers/move_worker_spec.rb
@@ -9,7 +9,8 @@ describe MoveWorker do
   let(:source_account)   { Fabricate(:account, protocol: :activitypub, domain: 'example.com') }
   let(:target_account)   { Fabricate(:account, protocol: :activitypub, domain: 'example.com') }
   let(:local_user)       { Fabricate(:user) }
-  let!(:account_note)    { Fabricate(:account_note, account: local_user.account, target_account: source_account) }
+  let(:comment)          { 'old note prior to move' }
+  let!(:account_note)    { Fabricate(:account_note, account: local_user.account, target_account: source_account, comment: comment) }
 
   let(:block_service) { double }
 
@@ -26,19 +27,37 @@ describe MoveWorker do
   end
 
   shared_examples 'user note handling' do
-    it 'copies user note' do
-      subject.perform(source_account.id, target_account.id)
-      expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(source_account.acct)
-      expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(account_note.comment)
+    context 'when user notes are short enough' do
+      it 'copies user note with prelude' do
+        subject.perform(source_account.id, target_account.id)
+        expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(source_account.acct)
+        expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(account_note.comment)
+      end
+
+      it 'merges user notes when needed' do
+        new_account_note = AccountNote.create!(account: account_note.account, target_account: target_account, comment: 'new note prior to move')
+
+        subject.perform(source_account.id, target_account.id)
+        expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(source_account.acct)
+        expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(account_note.comment)
+        expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(new_account_note.comment)
+      end
     end
 
-    it 'merges user notes when needed' do
-      new_account_note = AccountNote.create!(account: account_note.account, target_account: target_account, comment: 'new note prior to move')
+    context 'when user notes are too long' do
+      let(:comment) { 'abc' * 333 }
 
-      subject.perform(source_account.id, target_account.id)
-      expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(source_account.acct)
-      expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(account_note.comment)
-      expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(new_account_note.comment)
+      it 'copies user note without prelude' do
+        subject.perform(source_account.id, target_account.id)
+        expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(account_note.comment)
+      end
+
+      it 'keeps user notes unchanged' do
+        new_account_note = AccountNote.create!(account: account_note.account, target_account: target_account, comment: 'new note prior to move')
+
+        subject.perform(source_account.id, target_account.id)
+        expect(AccountNote.find_by(account: account_note.account, target_account: target_account).comment).to include(new_account_note.comment)
+      end
     end
   end