diff --git a/ChangeLog b/ChangeLog
index 4ffda03c83..5c4dfbefd3 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,7 @@
+Wed Apr  8 11:46:26 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
+
+	* lib/mkmf.rb (what_type?): fixed typo.
+
 Wed Apr  8 09:45:58 2009  Nobuyoshi Nakada  <nobu@ruby-lang.org>
 
 	* configure.in (LIBRUBY_SO): removed redundant additional version
diff --git a/lib/mkmf.rb b/lib/mkmf.rb
index ddc3e3e147..04bdbdf4a7 100644
--- a/lib/mkmf.rb
+++ b/lib/mkmf.rb
@@ -1037,7 +1037,7 @@ def what_type?(type, member = nil, headers = nil, &b)
   end
   prelude = cpp_include(headers).split(/$/)
   prelude << "typedef #{type} rbcv_typedef_;\n"
-  prelude << "static rbcv_typedef_ #{var_};\n"
+  prelude << "static rbcv_typedef_ #{var};\n"
   prelude << "extern rbcv_typedef_ #{func};\n"
   headers = [prelude]
   if member