diff --git a/Rakefile b/Rakefile
index 2b866a8f5..22e9c463f 100644
--- a/Rakefile
+++ b/Rakefile
@@ -152,7 +152,7 @@ file presym_inc => presym_file do
 end
 
 task :gensym => presym_inc
-depfiles += ["gensym"]
+depfiles.unshift "gensym"
 
 depfiles += MRuby.targets.map { |n, t|
   t.libraries