diff --git a/system/core/Security.php b/system/core/Security.php
index 0dc74a2..181ace2 100755
--- a/system/core/Security.php
+++ b/system/core/Security.php
@@ -565,7 +565,7 @@
 		}
 
 		// Unfortunately, none of the following PRNGs is guaranteed to exist ...
-		if (defined(MCRYPT_DEV_URANDOM) && ($output = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)) !== FALSE)
+		if (defined('MCRYPT_DEV_URANDOM') && ($output = mcrypt_create_iv($length, MCRYPT_DEV_URANDOM)) !== FALSE)
 		{
 			return $output;
 		}