diff --git a/system/codeigniter/Common.php b/system/codeigniter/Common.php
index 8c08d35..9212f07 100644
--- a/system/codeigniter/Common.php
+++ b/system/codeigniter/Common.php
@@ -32,16 +32,23 @@
 /**
  * Tests for file writability
  *
- * is_writable() returns TRUE on Windows servers
- * when you really can't write to the file
- * as the OS reports to PHP as FALSE only if the
- * read-only attribute is marked.  Ugh?
+ * is_writable() returns TRUE on Windows servers when you really can't write to 
+ * the file, based on the read-only attribute.  is_writable() is also unreliable
+ * on Unix servers if safe_mode is on. 
  *
  * @access	private
  * @return	void
  */
 function is_really_writable($file)
-{
+{	
+	// If we're on a Unix server with safe_mode off we call is_writable
+	if (DIRECTORY_SEPARATOR == '/' AND @ini_get("safe_mode") == FALSE)
+	{
+		return is_writable($file);
+	}
+
+	// For windows servers and safe_mode "on" installations we'll actually
+	// write a file then read it.  Bah...
 	if (is_dir($file))
 	{
 		$file = rtrim($file, '/').'/'.md5(rand(1,100));