diff --git a/ChangeLog b/ChangeLog
index 27ac7ff002..d836f9d008 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+Fri May  8 19:17:02 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/mkmf.rb (check_sizeof): fixed wrong recuring result for
+	  intrinsic types.
+
 Fri May  8 10:14:08 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* Makefile.in, configure.in, win32/Makefile.sub (RUBY_BASE_NAME):
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index d24c87f5cd..45346bfdbc 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -989,10 +989,14 @@ def check_sizeof(type, headers = nil, &b)
     x ? super : "failed"
   end
   checking_for checking_message("size of #{type}", headers), fmt do
-    if ((size = UNIVERSAL_INTS.find {|t|
-           try_static_assert("#{expr} == sizeof(#{t})", prelude, &b)
-         }) or
-        size = try_constant(expr, prelude, &b))
+    if UNIVERSAL_INTS.include?(type)
+      type
+    elsif size = UNIVERSAL_INTS.find {|t|
+        try_static_assert("#{expr} == sizeof(#{t})", prelude, opts, &b)
+      }
+      $defs.push(format("-DSIZEOF_%s=SIZEOF_%s", type.tr_cpp, size.tr_cpp))
+      size
+    elsif size = try_constant(expr, prelude, opts, &b)
       $defs.push(format("-DSIZEOF_%s=%s", type.tr_cpp, size))
       size
     end