diff --git a/docs/Gemfile b/docs/Gemfile
index f9eb77a02..354efb4c3 100644
--- a/docs/Gemfile
+++ b/docs/Gemfile
@@ -10,5 +10,5 @@ platforms :mingw, :x64_mingw, :mswin, :jruby do
   gem "tzinfo-data"
 end
 
-gem "wdm", "~> 0.1.1", :platforms => [:mingw, :x64_mingw, :mswin]
+gem "wdm", "~> 0.2.0", :platforms => [:mingw, :x64_mingw, :mswin]