diff --git a/public/index.php b/public/index.php
index d031ea10944a..0cdc61b05ddd 100644
--- a/public/index.php
+++ b/public/index.php
@@ -43,6 +43,11 @@
 require_once SYSTEMPATH . 'Config/DotEnv.php';
 (new CodeIgniter\Config\DotEnv(ROOTPATH))->load();
 
+// Define ENVIRONMENT
+if (! defined('ENVIRONMENT')) {
+    define('ENVIRONMENT', env('CI_ENVIRONMENT', 'production'));
+}
+
 /*
  * ---------------------------------------------------------------
  * GRAB OUR CODEIGNITER INSTANCE
diff --git a/spark b/spark
index f2ba3f305ceb..2ea79d5ccdaf 100755
--- a/spark
+++ b/spark
@@ -78,6 +78,11 @@ require rtrim($paths->systemDirectory, '\\/ ') . DIRECTORY_SEPARATOR . 'bootstra
 require_once SYSTEMPATH . 'Config/DotEnv.php';
 (new CodeIgniter\Config\DotEnv(ROOTPATH))->load();
 
+// Define ENVIRONMENT
+if (! defined('ENVIRONMENT')) {
+    define('ENVIRONMENT', env('CI_ENVIRONMENT', 'production'));
+}
+
 // Grab our CodeIgniter
 $app = Config\Services::codeigniter();
 $app->initialize();
diff --git a/system/CodeIgniter.php b/system/CodeIgniter.php
index 8bdcc15bc16e..3664c0321fa2 100644
--- a/system/CodeIgniter.php
+++ b/system/CodeIgniter.php
@@ -200,7 +200,6 @@ public function __construct(App $config)
     public function initialize()
     {
         // Define environment variables
-        $this->detectEnvironment();
         $this->bootstrapEnvironment();
 
         // Setup Exception Handling
@@ -560,6 +559,8 @@ protected function handleRequest(?RouteCollectionInterface $routes, Cache $cache
      *     production
      *
      * @codeCoverageIgnore
+     *
+     * @deprecated 4.4.0 No longer used. Moved to index.php and spark.
      */
     protected function detectEnvironment()
     {