diff --git a/app/models/account.rb b/app/models/account.rb
index 2bf00b2be59..b10b2af4236 100644
--- a/app/models/account.rb
+++ b/app/models/account.rb
@@ -71,6 +71,7 @@ class Account < ApplicationRecord
   MENTION_RE    = %r{(?<![=/[:word:]])@((#{USERNAME_RE})(?:@[[:word:].-]+[[:word:]]+)?)}i
   URL_PREFIX_RE = %r{\Ahttp(s?)://[^/]+}
   USERNAME_ONLY_RE = /\A#{USERNAME_RE}\z/i
+  USERNAME_LENGTH_LIMIT = 30
 
   include Attachmentable # Load prior to Avatar & Header concerns
 
@@ -100,7 +101,7 @@ class Account < ApplicationRecord
   validates :uri, presence: true, unless: :local?, on: :create
 
   # Local user validations
-  validates :username, format: { with: /\A[a-z0-9_]+\z/i }, length: { maximum: 30 }, if: -> { local? && will_save_change_to_username? && actor_type != 'Application' }
+  validates :username, format: { with: /\A[a-z0-9_]+\z/i }, length: { maximum: USERNAME_LENGTH_LIMIT }, if: -> { local? && will_save_change_to_username? && actor_type != 'Application' }
   validates_with UnreservedUsernameValidator, if: -> { local? && will_save_change_to_username? && actor_type != 'Application' }
   validates :display_name, length: { maximum: 30 }, if: -> { local? && will_save_change_to_display_name? }
   validates :note, note_length: { maximum: 500 }, if: -> { local? && will_save_change_to_note? }