diff --git a/system/HTTP/IncomingRequest.php b/system/HTTP/IncomingRequest.php
index 45dab098ca15..9c04850097cb 100755
--- a/system/HTTP/IncomingRequest.php
+++ b/system/HTTP/IncomingRequest.php
@@ -468,30 +468,6 @@ public function setPath(string $path, ?App $config = null)
         return $this;
     }
 
-    /**
-     * @deprecated Moved to SiteURIFactory.
-     */
-    private function determineHost(App $config, string $baseURL): string
-    {
-        $host = parse_url($baseURL, PHP_URL_HOST);
-
-        if (empty($config->allowedHostnames)) {
-            return $host;
-        }
-
-        // Update host if it is valid.
-        $httpHostPort = $this->getServer('HTTP_HOST');
-        if ($httpHostPort !== null) {
-            [$httpHost] = explode(':', $httpHostPort, 2);
-
-            if (in_array($httpHost, $config->allowedHostnames, true)) {
-                $host = $httpHost;
-            }
-        }
-
-        return $host;
-    }
-
     /**
      * Returns the URI path relative to baseURL,
      * running detection as necessary.