diff --git a/app/models/username_validator.rb b/app/models/username_validator.rb
index 1bb51491e67..747eb2f777e 100644
--- a/app/models/username_validator.rb
+++ b/app/models/username_validator.rb
@@ -138,6 +138,6 @@ class UsernameValidator
   end
 
   def self.allowed_char?(c)
-    c.match?(/[\w.-]/) || c.match?(SiteSetting.allowed_unicode_username_characters)
+    c.match?(/[\w.-]/) || c.match?(SiteSetting.allowed_unicode_username_characters_regex)
   end
 end