diff --git a/ChangeLog b/ChangeLog
index ccf50dc603..0a3237e729 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,6 @@
-Thu Nov 11 23:32:10 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+Thu Nov 11 23:38:32 2010  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* configure.in: ANSI C-conforming const and volatile are mandatory
 
 	* configure.in (AC_C_CONST, AC_C_INLINE, AC_C_VOLATILE): check
 	  before used in other checks.
diff --git a/configure.in b/configure.in
index b8b4478abc..10e9e8155e 100644
--- a/configure.in
+++ b/configure.in
@@ -485,6 +485,9 @@ AC_C_CHAR_UNSIGNED
 AC_C_INLINE
 AC_C_VOLATILE
 
+AS_CASE(":$ac_cv_c_const:$ac_cv_c_volatile:",
+    [*:no:*], [AC_MSG_ERROR(ANSI C-conforming const and volatile are mandatory)])
+
 AC_CHECK_TYPES([long long, off_t])
 
 AC_CACHE_CHECK([char bit], [rb_cv_char_bit],