diff --git a/mrbgem.rake b/mrbgem.rake
index eec30b1..db60984 100644
--- a/mrbgem.rake
+++ b/mrbgem.rake
@@ -99,11 +99,9 @@ MRuby::Gem::Specification.new('mruby-onig-regexp') do |spec|
       objs.each{|obj| file obj => oniguruma_lib }
     end
 
-    task :mruby_onig_regexp_with_compile_option do
-      cc.include_paths << oniguruma_dir
-      cc.defines += ['HAVE_ONIGMO_H']
-    end
-    file "#{dir}/src/mruby_onig_regexp.c" => [:mruby_onig_regexp_with_compile_option, oniguruma_lib]
+    cc.include_paths << oniguruma_dir
+    cc.defines += ['HAVE_ONIGMO_H']
+    file "#{dir}/src/mruby_onig_regexp.c" => oniguruma_lib
   end
 
   if spec.respond_to? :search_package and spec.search_package 'onigmo'