diff --git a/tests/codeigniter/libraries/Form_validation_test.php b/tests/codeigniter/libraries/Form_validation_test.php
index 905f663..0815300 100644
--- a/tests/codeigniter/libraries/Form_validation_test.php
+++ b/tests/codeigniter/libraries/Form_validation_test.php
@@ -259,6 +259,9 @@
 		// https://github.com/bcit-ci/CodeIgniter/issues/4415
 		$this->assertTrue($this->form_validation->valid_url('http://[::1]/ipv6'));
 
+		// URI scheme case-sensitivity: https://github.com/bcit-ci/CodeIgniter/pull/4758
+		$this->assertTrue($this->form_validation->valid_url('HtTp://127.0.0.1/'));
+
 		$this->assertFalse($this->form_validation->valid_url('htt://www.codeIgniter.com'));
 		$this->assertFalse($this->form_validation->valid_url(''));
 		$this->assertFalse($this->form_validation->valid_url('code igniter'));
diff --git a/user_guide_src/source/changelog.rst b/user_guide_src/source/changelog.rst
index 7527048..e95d509 100644
--- a/user_guide_src/source/changelog.rst
+++ b/user_guide_src/source/changelog.rst
@@ -17,6 +17,7 @@
 -  Fixed a bug (#4737) - :doc:`Query Builder <database/query_builder>` didn't add an ``OFFSET`` when ``LIMIT`` is zero or unused.
 -  Fixed a regression (#4739) - :doc:`Email Library <libraries/email>` doesn't properly separate attachment bodies from headers.
 -  Fixed a bug (#4754) - :doc:`Unit Testing Library <libraries/unit_testing>` method ``result()`` didn't translate ``res_datatype``.
+-  Fixed a bug (#4759) - :doc:`Form Validation <libraries/form_validation>`, :doc:`Trackback <libraries/trackback>` and `XML-RPC <libraries/xmlrpc>` libraries treated URI schemes in a case-sensitive manner.
 
 Version 3.1.0
 =============