diff --git a/system/codeigniter/Common.php b/system/codeigniter/Common.php
index eb9dce6..73ff019 100644
--- a/system/codeigniter/Common.php
+++ b/system/codeigniter/Common.php
@@ -62,7 +62,7 @@
 	// write a file then read it.  Bah...
 	if (is_dir($file))
 	{
-		$file = rtrim($file, '/').'/'.md5(rand(1,100));
+		$file = rtrim($file, '/').'/'.md5(mt_rand(1,100).mt_rand(1,100));
 
 		if (($fp = @fopen($file, FOPEN_WRITE_CREATE)) === FALSE)
 		{
diff --git a/user_guide/changelog.html b/user_guide/changelog.html
index 6ec6cd3..a6eaef1 100644
--- a/user_guide/changelog.html
+++ b/user_guide/changelog.html
@@ -76,6 +76,7 @@
 
 <h3>Bug fixes for 1.7.3</h3>
 <ul>
+	<li>Increased randomness with<kbd>is_really_writable()</kbd> to avoid file collisions when hundreds or thousands of requests occur at once.</li>
 	<li>Fixed or clarified assorted user guide typos or examples.</li>
 </ul>