diff --git a/mix.exs b/mix.exs
index d296dca..9a0908f 100644
--- a/mix.exs
+++ b/mix.exs
@@ -20,7 +20,8 @@ defmodule PublicSuffix.Mixfile do
       # rules file. So it is not needed at runtime.
       applications: [
         :logger
-      ]
+      ],
+      extra_applications: [:idna]
     ]
   end