diff --git a/admin/cli/install.php b/admin/cli/install.php
index fcd25b248fa..1d97e606cd0 100644
--- a/admin/cli/install.php
+++ b/admin/cli/install.php
@@ -189,6 +189,14 @@ require_once($CFG->libdir.'/adminlib.php');
 require_once($CFG->libdir.'/componentlib.class.php');
 require_once($CFG->dirroot.'/cache/lib.php');
 
+// Register our classloader, in theory somebody might want to replace it to load other hacked core classes.
+// Required because the database checks below lead to session interaction which is going to lead us to requiring autoloaded classes.
+if (defined('COMPONENT_CLASSLOADER')) {
+    spl_autoload_register(COMPONENT_CLASSLOADER);
+} else {
+    spl_autoload_register('core_component::classloader');
+}
+
 require($CFG->dirroot.'/version.php');
 $CFG->target_release = $release;
 
diff --git a/install.php b/install.php
index 899ebd35e38..c1c40ca6823 100644
--- a/install.php
+++ b/install.php
@@ -221,6 +221,14 @@ ini_set('include_path', $CFG->libdir.'/pear' . PATH_SEPARATOR . ini_get('include
 //point zend include path to moodles lib/zend so that includes and requires will search there for files before anywhere else
 ini_set('include_path', $CFG->libdir.'/zend' . PATH_SEPARATOR . ini_get('include_path'));
 
+// Register our classloader, in theory somebody might want to replace it to load other hacked core classes.
+// Required because the database checks below lead to session interaction which is going to lead us to requiring autoloaded classes.
+if (defined('COMPONENT_CLASSLOADER')) {
+    spl_autoload_register(COMPONENT_CLASSLOADER);
+} else {
+    spl_autoload_register('core_component::classloader');
+}
+
 require('version.php');
 $CFG->target_release = $release;