Writing nulls in cache should really be fine.

Sources/StoryBB/Cache/File.php

@@ -120,7 +120,7 @@ public function putData($key, $value, $ttl = null)
 			@unlink($cachedir . '/data_' . $key . '.php');
 		else
 		{
-			$cache_data = '<' . '?' . 'php if (!defined(\'STORYBB\')) die; if (' . (time() + $ttl) . ' < time()) $expired = true; else{$expired = false; $value = \'' . addcslashes($value, '\\\'') . '\';}' . '?' . '>';
+			$cache_data = '<' . '?' . 'php if (!defined(\'STORYBB\')) die; if (' . (time() + $ttl) . ' < time()) $expired = true; else{$expired = false; $value = \'' . addcslashes($value, "\0" . '\\\'') . '\';}' . '?' . '>';
 
 			// Write out the cache file, check that the cache write was successful; all the data must be written
 			// If it fails due to low diskspace, or other, remove the cache file