1 files changed, 3 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/validations/uniqueness.rb b/activerecord/lib/active_record/validations/uniqueness.rb
index fb745af125..88ae62c681 100644
--- a/activerecord/lib/active_record/validations/uniqueness.rb
+++ b/activerecord/lib/active_record/validations/uniqueness.rb
@@ -12,7 +12,7 @@ module ActiveRecord
           raise ArgumentError, "#{options[:scope]} is not supported format for :scope option. " \
             "Pass a symbol or an array of symbols instead: `scope: :user_id`"
         end
-        super({ case_sensitive: true }.merge!(options))
+        super
         @klass = options[:class]
       end
 
@@ -62,6 +62,8 @@ module ActiveRecord
 
           if bind.nil?
             attr.eq(bind)
+          elsif !options.key?(:case_sensitive)
+            klass.connection.default_uniqueness_comparison(attr, bind)
           elsif options[:case_sensitive]
             klass.connection.case_sensitive_comparison(attr, bind)
           else