diff --git a/ChangeLog b/ChangeLog
index 38a70bd606..4525808225 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri Jul 11 15:59:42 2014  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
+
+	* array.c: Clarify documentation for Array#insert.
+	  [ruby-core:62934] [Bug #9901]
+
 Fri Jul 11 15:39:36 2014  SHIBATA Hiroshi  <shibata.hiroshi@gmail.com>
 
 	* io.c: Improve Documentation by @dapplebeforedawn.
diff --git a/array.c b/array.c
index dc1dad6d16..0bfbfb4fd1 100644
--- a/array.c
+++ b/array.c
@@ -1742,7 +1742,9 @@ fixnum:
  *  Inserts the given values before the element with the given +index+.
  *
  *  Negative indices count backwards from the end of the array, where +-1+ is
- *  the last element.
+ *  the last element. If a negative index is used, the given values will be
+ *  inserted after that element, so using an index of +-1+ will insert the
+ *  values at the end of the array.
  *
  *     a = %w{ a b c d }
  *     a.insert(2, 99)         #=> ["a", "b", 99, "c", "d"]