diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 76d76cb0dd185..e79487c68728b 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* Change validates_uniqueness_of :case_sensitive option default back to true (from [9160]).  Love your database columns, don't LOWER them.  [rick]
+
 * Ensure that save on child object fails for invalid belongs_to association. Closes #11555. [rubyruy]
 
 * Add support for interleaving migrations by storing which migrations have run in the new schema_migrations table. Closes #11493 [jordi]
diff --git a/activerecord/lib/active_record/validations.rb b/activerecord/lib/active_record/validations.rb
index bd1c67cd84819..86cda9aa66237 100755
--- a/activerecord/lib/active_record/validations.rb
+++ b/activerecord/lib/active_record/validations.rb
@@ -603,7 +603,7 @@ def validates_length_of(*attrs)
       # Configuration options:
       # * <tt>message</tt> - Specifies a custom error message (default is: "has already been taken")
       # * <tt>scope</tt> - One or more columns by which to limit the scope of the uniqueness constraint.
-      # * <tt>case_sensitive</tt> - Looks for an exact match.  Ignored by non-text columns (false by default).
+      # * <tt>case_sensitive</tt> - Looks for an exact match.  Ignored by non-text columns (true by default).
       # * <tt>allow_nil</tt> - If set to true, skips this validation if the attribute is null (default is: false)
       # * <tt>allow_blank</tt> - If set to true, skips this validation if the attribute is blank (default is: false)
       # * <tt>if</tt> - Specifies a method, proc or string to call to determine if the validation should
@@ -613,7 +613,7 @@ def validates_length_of(*attrs)
       #   not occur (e.g. :unless => :skip_validation, or :unless => Proc.new { |user| user.signup_step <= 2 }).  The
       #   method, proc or string should return or evaluate to a true or false value.
       def validates_uniqueness_of(*attr_names)
-        configuration = { :message => ActiveRecord::Errors.default_error_messages[:taken] }
+        configuration = { :message => ActiveRecord::Errors.default_error_messages[:taken], :case_sensitive => true }
         configuration.update(attr_names.extract_options!)
 
         validates_each(attr_names,configuration) do |record, attr_name, value|