diff --git a/lib/validators/password_validator.rb b/lib/validators/password_validator.rb
index bc4ae51b813..ced6b2f9909 100644
--- a/lib/validators/password_validator.rb
+++ b/lib/validators/password_validator.rb
@@ -18,7 +18,7 @@ class PasswordValidator < ActiveModel::EachValidator
       record.errors.add(attribute, :same_as_current)
     elsif SiteSetting.block_common_passwords && CommonPasswords.common_password?(value)
       record.errors.add(attribute, :common)
-    elsif value.split("").uniq.length < SiteSetting.password_unique_characters
+    elsif value.chars.uniq.length < SiteSetting.password_unique_characters
       record.errors.add(attribute, :unique_characters)
     end
   end