diff --git a/libraries/loader.php b/libraries/loader.php
index 5adca189bf340..ef2bb36840c77 100644
--- a/libraries/loader.php
+++ b/libraries/loader.php
@@ -438,6 +438,9 @@ public static function registerNamespace($namespace, $path, $reset = false, $pre
 			throw new RuntimeException('Library path ' . $path . ' cannot be found.', 500);
 		}
 
+		// Trim leading and trailing backslashes from namespace, allowing "\Parent\Child", "Parent\Child\" and "\Parent\Child\" to be treated the same way.
+		$namespace = trim($namespace, '\\');
+
 		// If the namespace is not yet registered or we have an explicit reset flag then set the path.
 		if ($reset || !isset(self::$namespaces[$type][$namespace]))
 		{
@@ -533,10 +536,10 @@ public static function loadByPsr4($class)
 		// Loop through registered namespaces until we find a match.
 		foreach (self::$namespaces['psr4'] as $ns => $paths)
 		{
-			$nsPath = trim(str_replace('\\', DIRECTORY_SEPARATOR, $ns), DIRECTORY_SEPARATOR);
-
-			if (strpos($class, $ns) === 0)
+			if (strpos($class, "{$ns}\\") === 0)
 			{
+				$nsPath = trim(str_replace('\\', DIRECTORY_SEPARATOR, $ns), DIRECTORY_SEPARATOR);
+
 				// Loop through paths registered to this namespace until we find a match.
 				foreach ($paths as $path)
 				{
diff --git a/tests/unit/stubs/DummyNamespace/DummyClass.php b/tests/unit/stubs/DummyNamespace/DummyClass.php
new file mode 100644
index 0000000000000..f2484e939dd62
--- /dev/null
+++ b/tests/unit/stubs/DummyNamespace/DummyClass.php
@@ -0,0 +1,29 @@
+<?php
+/**
+ * @package    Joomla.UnitTest
+ *
+ * @copyright  Copyright (C) 2005 - 2017 Open Source Matters, Inc. All rights reserved.
+ * @license    GNU General Public License version 2 or later; see LICENSE.txt
+ */
+namespace DummyNamespace;
+
+defined('JPATH_PLATFORM') or die;
+
+/**
+ * Dummy class, used for namespaced class loading tests.
+ *
+ * @package  None
+ *
+ * @since    __DEPLOY_VERSION__
+ */
+class DummyClass
+{
+	/**
+	 * Returns class name without namespace.
+	 * @return string
+	 */
+	public static function getName ()
+	{
+		return 'DummyClass';
+	}
+}
diff --git a/tests/unit/suites/libraries/joomla/JLoaderTest.php b/tests/unit/suites/libraries/joomla/JLoaderTest.php
index 886c62008a43e..1ec163a947da9 100644
--- a/tests/unit/suites/libraries/joomla/JLoaderTest.php
+++ b/tests/unit/suites/libraries/joomla/JLoaderTest.php
@@ -279,6 +279,21 @@ public function testLoadOverrideOriginalClass()
 		$this->assertEquals('Original Override Class', $oldClass->getName());
 	}
 
+	/**
+	 * Tests the JLoader::loadByPsr4 method.
+	 *
+	 * @return  void
+	 *
+	 * @since   __DEPLOY_VERSION__
+	 */
+	public function testLoadByPsr4()
+	{
+		// Register namespace at first. Odd leading and trailing backslashes must be automatically removed from namespace
+		JLoader::registerNamespace('\\DummyNamespace\\', JPATH_TEST_STUBS . '/DummyNamespace', $reset = true, $prepend = false, $type = 'psr4');
+
+		$this->assertThat(JLoader::loadByPsr4('DummyNamespace\DummyClass'), $this->isTrue(), 'Tests that the class file was loaded.');
+	}
+
 	/**
 	 * Tests the JLoader::registerAlias method if the alias is loaded when the original class is loaded.
 	 *
@@ -487,6 +502,32 @@ public function testRegisterNamespaceException()
 		JLoader::registerNamespace('Color', 'dummy');
 	}
 
+	/**
+	 * Tests the JLoader::registerNamespace method for namespace trimming of leading and trailing backslashes.
+	 *
+	 * @return  void
+	 *
+	 * @since   12.3
+	 */
+	public function testRegisterNamespaceTrimming()
+	{
+		// Try registering namespace with leading backslash.
+		$path = JPATH_TEST_STUBS . '/discover1';
+		JLoader::registerNamespace('\\discover1', $path);
+
+		$namespaces = JLoader::getNamespaces();
+
+		$this->assertContains($path, $namespaces['discover1']);
+
+		// Try registering namespace with trailing backslash.
+		$path = JPATH_TEST_STUBS . '/discover2';
+		JLoader::registerNamespace('discover2\\', $path);
+
+		$namespaces = JLoader::getNamespaces();
+
+		$this->assertContains($path, $namespaces['discover2']);
+	}
+
 	/**
 	 * Tests the JLoader::registerPrefix method.
 	 *