diff --git a/lib/vagrant/ui.rb b/lib/vagrant/ui.rb
index a9c9a67e9..bcbf16146 100644
--- a/lib/vagrant/ui.rb
+++ b/lib/vagrant/ui.rb
@@ -31,7 +31,14 @@ module Vagrant
     end
 
     # This is a UI implementation that does nothing.
-    class Silent < Interface; end
+    class Silent < Interface
+      def ask(*args)
+        super
+
+        # Silent can't do this, obviously.
+        raise Errors::UIExpectsTTY
+      end
+    end
 
     # This is a UI implementation that outputs the text as is. It
     # doesn't add any color.