diff --git a/xdiff.php b/xdiff.php
index 734e93e..a72fdb5 100644
--- a/xdiff.php
+++ b/xdiff.php
@@ -359,6 +359,10 @@ class xdiff
   /** This function return the next common part between both arrays starting at
     * position $i for $array1 and $j for array2
     * Return empty string if no common lines was found
+    * @param array $array1 The first array to compare
+    * @param array $array2 The second array to compare
+    * @param integer $i The position pointer on first array
+    * @param integer $j The position pointer on second array
     * @return string
     */
   private function lcs ($array1, $array2, $i, $j)