diff --git a/phpBB/includes/constants.php b/phpBB/includes/constants.php
index 01300c8992..33b7d960ba 100644
--- a/phpBB/includes/constants.php
+++ b/phpBB/includes/constants.php
@@ -177,10 +177,10 @@ define('REFERER_VALIDATE_HOST', 1);
 define('REFERER_VALIDATE_PATH', 2);
 
 // phpbb_chmod() permissions
-define('CHMOD_ALL', 7);
+@define('CHMOD_ALL', 7);
 define('CHMOD_READ', 4);
 define('CHMOD_WRITE', 2);
-define('CHMOD_EXECUTE', 1);
+@define('CHMOD_EXECUTE', 1);
 
 // Additional constants
 define('VOTE_CONVERTED', 127);
diff --git a/phpBB/install/index.php b/phpBB/install/index.php
index e3bfcba499..613afa728c 100644
--- a/phpBB/install/index.php
+++ b/phpBB/install/index.php
@@ -230,6 +230,14 @@ include(PHPBB_ROOT_PATH . 'language/' . $language . '/acp/board.' . PHP_EXT);
 include(PHPBB_ROOT_PATH . 'language/' . $language . '/install.' . PHP_EXT);
 include(PHPBB_ROOT_PATH . 'language/' . $language . '/posting.' . PHP_EXT);
 
+// usually we would need every single constant here - and it would be consistent. For 3.0.x, use a dirty hack... :(
+
+// Define needed constants
+define('CHMOD_ALL', 7);
+define('CHMOD_READ', 4);
+define('CHMOD_WRITE', 2);
+define('CHMOD_EXECUTE', 1);
+
 $mode = request_var('mode', 'overview');
 $sub = request_var('sub', '');