diff --git a/ChangeLog b/ChangeLog
index a92fc73494..d175701fed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Sun Jan  4 13:05:09 2015  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
+
+	* string.c: improve docs for String#<=>. [ruby-core:65399][Feature #10322]
+	  Patch by gogo tanaka.
+
 Sun Jan  4 12:42:24 2015  Ayumu AIZAWA  <ayumu.aizawa@gmail.com>
 
 	* array.c: improve docs for Array#reject. [ruby-core:65324][misc #10307]
diff --git a/string.c b/string.c
index 13c89b167b..c8707c62a6 100644
--- a/string.c
+++ b/string.c
@@ -2638,6 +2638,7 @@ rb_str_eql(VALUE str1, VALUE str2)
  *     "abcdef" <=> "abcdef"    #=> 0
  *     "abcdef" <=> "abcdefg"   #=> -1
  *     "abcdef" <=> "ABCDEF"    #=> 1
+ *     "abcdef" <=> 1           #=> nil
  */
 
 static VALUE