diff --git a/ChangeLog b/ChangeLog
index 5543003b37..d23b3be3aa 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Sep  1 14:35:29 2010  NARUSE, Yui  <naruse@ruby-lang.org>
+
+	* array.c (rb_ary_rotate_m): fix typo of rdoc.
+	  patched by Andrei Kulakov [ruby-core:31975]
+
 Wed Sep  1 14:33:36 2010  NARUSE, Yui  <naruse@ruby-lang.org>
 
 	* enum.c (enum_zip): fix typo of rdoc.
diff --git a/array.c b/array.c
index 026079b445..4e0585c6fd 100644
--- a/array.c
+++ b/array.c
@@ -1899,7 +1899,7 @@ rb_ary_rotate_bang(int argc, VALUE *argv, VALUE ary)
 
 /*
  *  call-seq:
- *     ary.rotate([n = 1]) -> new_ary
+ *     ary.rotate([cnt = 1]) -> new_ary
  *
  *  Returns new array by rotating +self+, whose first element is the
  *  element at +cnt+ in +self+.  If +cnt+ is negative then it rotates