diff --git a/ChangeLog b/ChangeLog
index 3d43abf502..bb489ff071 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Wed Nov  4 15:45:59 2015  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
+
+	* class.c: fix documentation for rb_define_class{_id}_under.
+	  [fix GH-991][ci skip] Patch by @kachick
+
 Wed Nov  4 15:40:45 2015  SHIBATA Hiroshi  <hsbt@ruby-lang.org>
 
 	* method.h: fix typo. Patch by @davydovanton
diff --git a/class.c b/class.c
index 7a9db63dcc..f95890bbc4 100644
--- a/class.c
+++ b/class.c
@@ -666,7 +666,7 @@ rb_define_class(const char *name, VALUE super)
  * \return the created class
  * \throw TypeError if the constant name \a name is already taken but
  *                  the constant is not a \c Class.
- * \throw NameError if the class is already defined but the class can not
+ * \throw TypeError if the class is already defined but the class can not
  *                  be reopened because its superclass is not \a super.
  * \post top-level constant named \a name refers the returned class.
  *
@@ -689,7 +689,7 @@ rb_define_class_under(VALUE outer, const char *name, VALUE super)
  * \return the created class
  * \throw TypeError if the constant name \a name is already taken but
  *                  the constant is not a \c Class.
- * \throw NameError if the class is already defined but the class can not
+ * \throw TypeError if the class is already defined but the class can not
  *                  be reopened because its superclass is not \a super.
  * \post top-level constant named \a name refers the returned class.
  *