diff --git a/ChangeLog b/ChangeLog
index c0ed20adf7..08d11c9400 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Thu Oct  6 10:37:13 2016  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
+
+	* enum.c: Add reduce/inject alias note.
+	  [fix GH-1400][ci skip] Patch by @getaaron
+
 Thu Oct  6 10:30:27 2016  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* thread.c (update_coverage): check coverage values, and ignore
diff --git a/enum.c b/enum.c
index 625097c636..ff14cc87a0 100644
--- a/enum.c
+++ b/enum.c
@@ -705,6 +705,9 @@ ary_inject_op(VALUE ary, VALUE init, VALUE op)
  *  operation, specified by a block or a symbol that names a
  *  method or operator.
  *
+ *  The <i>inject</i> and <i>reduce</i> methods are aliases. There
+ *  is no performance benefit to either.
+ *
  *  If you specify a block, then for each element in <i>enum</i>
  *  the block is passed an accumulator value (<i>memo</i>) and the element.
  *  If you specify a symbol instead, then each element in the collection