diff --git a/file.php b/file.php
index 09214fb..301b156 100644
--- a/file.php
+++ b/file.php
@@ -183,12 +183,13 @@ class file
 
   /** Write a string to a file
     * @param string $filename Path to the file where to write the data
-    * @param The data to write
+    * @param string $data The data to write
+    * @param int|null $flags The optional flags
     * @return the length of the data stored
     * @throws If parent directory not exists, is not writeable, or the file
     *         exists and is not writeable
     */
-  public function file_put_contents ($filename, $data, $flags)
+  public function file_put_contents ($filename, $data, $flags=0)
   {
     $this->debug (2, "file_put_contents ($filename)");
     $filename = $this->realpath ($filename);