diff --git a/install/lib/installer_base.lib.php b/install/lib/installer_base.lib.php
index 6cc4de996ab17a97bcbc827c372b87110a6a06ef..81b90aa02dc2ad8e87f7778c87bb6fba2bea7462 100644
--- a/install/lib/installer_base.lib.php
+++ b/install/lib/installer_base.lib.php
@@ -246,6 +246,8 @@ class installer_base {
 
 	//** Check prerequisites
 	public function check_prerequisites() {
+		global $conf;
+		
 		$msg = '';
 
 		if ($conf['default_php'] != '') {