diff --git a/ChangeLog b/ChangeLog
index 4407884794..e89c8d1e8c 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+Thu Mar 28 07:05:25 2013  Tanaka Akira  <akr@fsij.org>
+
+	* include/ruby/intern.h: Delete redundant inclusions caused by
+	  AC_INCLUDES_DEFAULT in defines.h.
+
+	* include/ruby/defines.h: Ditto.
+
+	* include/ruby/ruby.h: Ditto.
+
+	* include/ruby/st.h: Ditto.
+
 Thu Mar 28 06:51:31 2013  Tanaka Akira  <akr@fsij.org>
 
 	* include/ruby/defines.h: Fix a compilation error on NetBSD,
diff --git a/include/ruby/defines.h b/include/ruby/defines.h
index 131b2222fc..c741b0ec28 100644
--- a/include/ruby/defines.h
+++ b/include/ruby/defines.h
@@ -59,10 +59,6 @@ extern "C" {
 
 #define RUBY
 
-# include <stddef.h>
-#ifdef HAVE_STDLIB_H
-# include <stdlib.h>
-#endif
 #ifdef __cplusplus
 # ifndef  HAVE_PROTOTYPES
 #  define HAVE_PROTOTYPES 1
diff --git a/include/ruby/intern.h b/include/ruby/intern.h
index ae265ec3c0..de430a9eaf 100644
--- a/include/ruby/intern.h
+++ b/include/ruby/intern.h
@@ -32,10 +32,6 @@ extern "C" {
 # include <varargs.h>
 #endif
 
-#if defined(HAVE_SYS_TYPES_H)
-#include <sys/types.h>
-#endif
-
 #include "ruby/st.h"
 
 #if defined __GNUC__ && __GNUC__ >= 4
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 14b67ea067..eba50ea114 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -26,6 +26,8 @@ extern "C" {
 #include RUBY_EXTCONF_H
 #endif
 
+#include "defines.h"
+
 #define NORETURN_STYLE_NEW 1
 #ifndef NORETURN
 # define NORETURN(x) x
@@ -47,27 +49,11 @@ extern "C" {
 #define PRINTF_ARGS(decl, string_index, first_to_check) decl
 #endif
 
-#ifdef HAVE_STRING_H
-# include <string.h>
-#else
-# include <strings.h>
-#endif
-
 #ifdef HAVE_INTRINSICS_H
 # include <intrinsics.h>
 #endif
 
-#ifdef HAVE_STDINT_H
-# include <stdint.h>
-#endif
-#ifdef HAVE_INTTYPES_H
-# include <inttypes.h>
-#endif
-
 #include <stdarg.h>
-#include <stdio.h>
-
-#include "defines.h"
 
 #if defined __GNUC__ && __GNUC__ >= 4
 #pragma GCC visibility push(default)
diff --git a/include/ruby/st.h b/include/ruby/st.h
index c2294a92c1..466bbcf5f6 100644
--- a/include/ruby/st.h
+++ b/include/ruby/st.h
@@ -14,19 +14,6 @@ extern "C" {
 
 #include "ruby/defines.h"
 
-#if   defined STDC_HEADERS
-#include <stddef.h>
-#elif defined HAVE_STDLIB_H
-#include <stdlib.h>
-#endif
-
-#ifdef HAVE_STDINT_H
-# include <stdint.h>
-#endif
-#ifdef HAVE_INTTYPES_H
-# include <inttypes.h>
-#endif
-
 #if defined __GNUC__ && __GNUC__ >= 4
 #pragma GCC visibility push(default)
 #endif