diff --git a/lib/mruby/build/load_gems.rb b/lib/mruby/build/load_gems.rb
index 15331dd6f..9633c67bf 100644
--- a/lib/mruby/build/load_gems.rb
+++ b/lib/mruby/build/load_gems.rb
@@ -1,3 +1,5 @@
+require 'yaml'
+
 module MRuby
   module LoadGems