diff --git a/system/Session/Handlers/RedisHandler.php b/system/Session/Handlers/RedisHandler.php
index 93a601eade70..1e996b5f30b9 100644
--- a/system/Session/Handlers/RedisHandler.php
+++ b/system/Session/Handlers/RedisHandler.php
@@ -22,6 +22,8 @@
  */
 class RedisHandler extends BaseHandler
 {
+    private const DEFAULT_PORT = 6379;
+
     /**
      * phpRedis instance
      *
@@ -58,12 +60,27 @@ class RedisHandler extends BaseHandler
     protected $sessionExpiration = 7200;
 
     /**
+     * @param string $ipAddress User's IP address
+     *
      * @throws SessionException
      */
     public function __construct(AppConfig $config, string $ipAddress)
     {
         parent::__construct($config, $ipAddress);
 
+        $this->setSavePath();
+
+        if ($this->matchIP === true) {
+            $this->keyPrefix .= $this->ipAddress . ':';
+        }
+
+        $this->sessionExpiration = empty($config->sessionExpiration)
+            ? (int) ini_get('session.gc_maxlifetime')
+            : (int) $config->sessionExpiration;
+    }
+
+    protected function setSavePath(): void
+    {
         if (empty($this->savePath)) {
             throw SessionException::forEmptySavepath();
         }
@@ -75,24 +92,16 @@ public function __construct(AppConfig $config, string $ipAddress)
 
             $this->savePath = [
                 'host'     => $matches[1],
-                'port'     => empty($matches[2]) ? null : $matches[2],
+                'port'     => empty($matches[2]) ? self::DEFAULT_PORT : $matches[2],
                 'password' => preg_match('#auth=([^\s&]+)#', $matches[3], $match) ? $match[1] : null,
-                'database' => preg_match('#database=(\d+)#', $matches[3], $match) ? (int) $match[1] : null,
-                'timeout'  => preg_match('#timeout=(\d+\.\d+)#', $matches[3], $match) ? (float) $match[1] : null,
+                'database' => preg_match('#database=(\d+)#', $matches[3], $match) ? (int) $match[1] : 0,
+                'timeout'  => preg_match('#timeout=(\d+\.\d+|\d+)#', $matches[3], $match) ? (float) $match[1] : 0.0,
             ];
 
             preg_match('#prefix=([^\s&]+)#', $matches[3], $match) && $this->keyPrefix = $match[1];
         } else {
             throw SessionException::forInvalidSavePathFormat($this->savePath);
         }
-
-        if ($this->matchIP === true) {
-            $this->keyPrefix .= $this->ipAddress . ':';
-        }
-
-        $this->sessionExpiration = empty($config->sessionExpiration)
-            ? (int) ini_get('session.gc_maxlifetime')
-            : (int) $config->sessionExpiration;
     }
 
     /**
@@ -266,14 +275,15 @@ public function gc($max_lifetime)
      */
     protected function lockSession(string $sessionID): bool
     {
+        $lockKey = $this->keyPrefix . $sessionID . ':lock';
+
         // PHP 7 reuses the SessionHandler object on regeneration,
         // so we need to check here if the lock key is for the
         // correct session ID.
-        if ($this->lockKey === $this->keyPrefix . $sessionID . ':lock') {
+        if ($this->lockKey === $lockKey) {
             return $this->redis->expire($this->lockKey, 300);
         }
 
-        $lockKey = $this->keyPrefix . $sessionID . ':lock';
         $attempt = 0;
 
         do {
diff --git a/tests/system/Session/Handlers/Database/RedisHandlerTest.php b/tests/system/Session/Handlers/Database/RedisHandlerTest.php
new file mode 100644
index 000000000000..004eba2842eb
--- /dev/null
+++ b/tests/system/Session/Handlers/Database/RedisHandlerTest.php
@@ -0,0 +1,127 @@
+<?php
+
+/**
+ * This file is part of CodeIgniter 4 framework.
+ *
+ * (c) CodeIgniter Foundation <admin@codeigniter.com>
+ *
+ * For the full copyright and license information, please view
+ * the LICENSE file that was distributed with this source code.
+ */
+
+namespace CodeIgniter\Session\Handlers\Database;
+
+use CodeIgniter\Session\Handlers\RedisHandler;
+use CodeIgniter\Test\CIUnitTestCase;
+use Config\App as AppConfig;
+use Redis;
+
+/**
+ * @requires extension redis
+ *
+ * @internal
+ */
+final class RedisHandlerTest extends CIUnitTestCase
+{
+    private string $sessionName     = 'ci_session';
+    private string $sessionSavePath = 'tcp://127.0.0.1:6379';
+    private string $userIpAddress   = '127.0.0.1';
+
+    private function getInstance($options = [])
+    {
+        $defaults = [
+            'sessionDriver'            => RedisHandler::class,
+            'sessionCookieName'        => $this->sessionName,
+            'sessionExpiration'        => 7200,
+            'sessionSavePath'          => $this->sessionSavePath,
+            'sessionMatchIP'           => false,
+            'sessionTimeToUpdate'      => 300,
+            'sessionRegenerateDestroy' => false,
+            'cookieDomain'             => '',
+            'cookiePrefix'             => '',
+            'cookiePath'               => '/',
+            'cookieSecure'             => false,
+            'cookieSameSite'           => 'Lax',
+        ];
+
+        $config    = array_merge($defaults, $options);
+        $appConfig = new AppConfig();
+
+        foreach ($config as $key => $c) {
+            $appConfig->{$key} = $c;
+        }
+
+        return new RedisHandler($appConfig, $this->userIpAddress);
+    }
+
+    public function testSavePathTimeoutFloat()
+    {
+        $handler = $this->getInstance(
+            ['sessionSavePath' => 'tcp://127.0.0.1:6379?timeout=2.5']
+        );
+
+        $savePath = $this->getPrivateProperty($handler, 'savePath');
+
+        $this->assertSame(2.5, $savePath['timeout']);
+    }
+
+    public function testSavePathTimeoutInt()
+    {
+        $handler = $this->getInstance(
+            ['sessionSavePath' => 'tcp://127.0.0.1:6379?timeout=10']
+        );
+
+        $savePath = $this->getPrivateProperty($handler, 'savePath');
+
+        $this->assertSame(10.0, $savePath['timeout']);
+    }
+
+    public function testOpen()
+    {
+        $handler = $this->getInstance();
+        $this->assertTrue($handler->open($this->sessionSavePath, $this->sessionName));
+    }
+
+    public function testWrite()
+    {
+        $handler = $this->getInstance();
+        $handler->open($this->sessionSavePath, $this->sessionName);
+        $handler->read('555556b43phsnnf8if6bo33b635e4447');
+
+        $data = <<<'DATA'
+            __ci_last_regenerate|i:1664607454;_ci_previous_url|s:32:"http://localhost:8080/index.php/";key|s:5:"value";
+            DATA;
+        $this->assertTrue($handler->write('555556b43phsnnf8if6bo33b635e4447', $data));
+
+        $handler->close();
+    }
+
+    public function testReadSuccess()
+    {
+        $handler = $this->getInstance();
+        $handler->open($this->sessionSavePath, $this->sessionName);
+
+        $expected = <<<'DATA'
+            __ci_last_regenerate|i:1664607454;_ci_previous_url|s:32:"http://localhost:8080/index.php/";key|s:5:"value";
+            DATA;
+        $this->assertSame($expected, $handler->read('555556b43phsnnf8if6bo33b635e4447'));
+
+        $handler->close();
+    }
+
+    public function testReadFailure()
+    {
+        $handler = $this->getInstance();
+        $handler->open($this->sessionSavePath, $this->sessionName);
+
+        $this->assertSame('', $handler->read('123456b43phsnnf8if6bo33b635e4321'));
+
+        $handler->close();
+    }
+
+    public function testGC()
+    {
+        $handler = $this->getInstance();
+        $this->assertSame(1, $handler->gc(3600));
+    }
+}