diff --git a/ChangeLog b/ChangeLog
index 7fb483d7b6..f16eab8e27 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,9 @@
+Fri Mar 16 14:27:11 2012  Shugo Maeda  <shugo@ruby-lang.org>
+
+	* vm_eval.c (rb_mod_module_eval): fix the documentation of
+	  class_eval to mention constant lookup.  [ruby-core:41718]
+	  [Bug #5777]
+
 Fri Mar 16 14:10:45 2012  Shugo Maeda  <shugo@ruby-lang.org>
 
 	* lib/net/imap.rb (initialize): raise Net::IMAP::Error when the
diff --git a/vm_eval.c b/vm_eval.c
index 398c344bc5..f9eef4288a 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -1379,10 +1379,11 @@ rb_obj_instance_exec(int argc, VALUE *argv, VALUE self)
  *     mod.class_eval(string [, filename [, lineno]])  -> obj
  *     mod.module_eval {|| block }                     -> obj
  *
- *  Evaluates the string or block in the context of _mod_. This can
- *  be used to add methods to a class. <code>module_eval</code> returns
- *  the result of evaluating its argument. The optional _filename_
- *  and _lineno_ parameters set the text for error messages.
+ *  Evaluates the string or block in the context of _mod_, except that when
+ *  a block is given, constant lookup is not affected. This can be used to
+ *  add methods to a class. <code>module_eval</code> returns the result of
+ *  evaluating its argument. The optional _filename_ and _lineno_ parameters
+ *  set the text for error messages.
  *
  *     class Thing
  *     end