diff --git a/app/models/account.rb b/app/models/account.rb
index d0ebf5a5e0..ac27c7923f 100644
--- a/app/models/account.rb
+++ b/app/models/account.rb
@@ -54,6 +54,8 @@ class Account < ApplicationRecord
   include Remotable
   include EmojiHelper
 
+  MAX_NOTE_LENGTH = 500
+
   enum protocol: [:ostatus, :activitypub]
 
   # Local users
@@ -288,7 +290,7 @@ class Account < ApplicationRecord
         note_without_metadata = note[(idx + YAML_END.length) .. -1]
       end
     end
-    if note_without_metadata.mb_chars.grapheme_length > 500
+    if note_without_metadata.mb_chars.grapheme_length > MAX_NOTE_LENGTH
       errors.add(:note, "can't be longer than 500 graphemes")
     end
   end
diff --git a/spec/controllers/api/v1/accounts/credentials_controller_spec.rb b/spec/controllers/api/v1/accounts/credentials_controller_spec.rb
index 461b8b34bb..247420d083 100644
--- a/spec/controllers/api/v1/accounts/credentials_controller_spec.rb
+++ b/spec/controllers/api/v1/accounts/credentials_controller_spec.rb
@@ -51,7 +51,9 @@ describe Api::V1::Accounts::CredentialsController do
 
       describe 'with invalid data' do
         before do
-          patch :update, params: { note: 'This is too long. ' * 10 }
+          note = 'This is too long. '
+          note = note + 'a' * (Account::MAX_NOTE_LENGTH - note.length + 1)
+          patch :update, params: { note: note }
         end
 
         it 'returns http unprocessable entity' do