I think your meant to use is_readable() here

krumo/class.krumo.php

@@ -15,11 +15,11 @@
 
 //////////////////////////////////////////////////////////////////////////////
 
-/**
-* backward compatibility: the DIR_SEP constant isn't used anymore
-*/
-if(!defined('DIR_SEP')) {
-	define('DIR_SEP', DIRECTORY_SEPARATOR);
+/**
+* backward compatibility: the DIR_SEP constant isn't used anymore
+*/
+if(!defined('DIR_SEP')) {
+	define('DIR_SEP', DIRECTORY_SEPARATOR);
 	}
 /**
 * backward compatibility: the PATH_SEPARATOR constant is availble since 4.3.0RC2
@@ -30,10 +30,10 @@ if (!defined('PATH_SEPARATOR')) {
 
 // -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
 
-/**
+/**
 * Set the KRUMO_DIR constant up with the absolute path to Krumo files. If it is 
 * not defined, include_path will be used. Set KRUMO_DIR only if any other module 
-* or application has not already set it up.
+* or application has not already set it up.
 */
 if (!defined('KRUMO_DIR')) {
 	define('KRUMO_DIR', dirname(__FILE__) . DIRECTORY_SEPARATOR);
@@ -274,7 +274,7 @@ This is a list of all HTTP request headers.
 			return false;
 			}
 
-		if (!readable(get_cfg_var('cfg_file_path'))) {
+		if (!is_readable(get_cfg_var('cfg_file_path'))) {
 			return false;
 			}
 
@@ -1301,4 +1301,4 @@ Function krumo() {
 
 //////////////////////////////////////////////////////////////////////////////
 
-?>
+?>