diff --git a/sinatra-contrib/lib/sinatra/namespace.rb b/sinatra-contrib/lib/sinatra/namespace.rb
index 63bf1d16..a82b02ef 100644
--- a/sinatra-contrib/lib/sinatra/namespace.rb
+++ b/sinatra-contrib/lib/sinatra/namespace.rb
@@ -1,5 +1,6 @@
 require 'backports'
 require 'sinatra/base'
+require 'mustermann'
 
 module Sinatra
 
diff --git a/sinatra-contrib/sinatra-contrib.gemspec b/sinatra-contrib/sinatra-contrib.gemspec
index 275ea377..8cd883fc 100644
--- a/sinatra-contrib/sinatra-contrib.gemspec
+++ b/sinatra-contrib/sinatra-contrib.gemspec
@@ -214,6 +214,7 @@ Gem::Specification.new do |s|
   ]
 
   s.add_dependency "sinatra", "> 1", "< 3"
+  s.add_dependency "mustermann",  "~> 0.4"
   s.add_dependency "backports", ">= 2.0"
   s.add_dependency "tilt",      ">= 1.3", "< 3"
   s.add_dependency "rack-test"