diff --git a/examples/sinatra/explorer.rb b/examples/sinatra/explorer.rb
index 0d5828201..481101e58 100644
--- a/examples/sinatra/explorer.rb
+++ b/examples/sinatra/explorer.rb
@@ -12,6 +12,14 @@ $LOAD_PATH.unshift(lib_dir)
 $LOAD_PATH.uniq!
 
 require 'rubygems'
+begin
+  gem 'rack', '= 1.2.0'
+  require 'rack'
+rescue LoadError
+  STDERR.puts "Missing dependencies."
+  STDERR.puts "sudo gem install rack -v 1.2.0"
+  exit(1)
+end
 begin
   require 'sinatra'
   require 'liquid'
diff --git a/tasks/gem.rake b/tasks/gem.rake
index 7e2dc4f55..06278d94f 100644
--- a/tasks/gem.rake
+++ b/tasks/gem.rake
@@ -26,6 +26,8 @@ namespace :gem do
     s.add_runtime_dependency('extlib', '>= 0.9.15')
 
     s.add_development_dependency('rack', '= 1.2.0')
+    s.add_development_dependency('sinatra', '>= 1.0')
+    s.add_development_dependency('liquid', '>= 2.2.2')
     s.add_development_dependency('rake', '>= 0.7.3')
     s.add_development_dependency('rspec', '~> 1.2.9')
     s.add_development_dependency('launchy', '>= 0.3.2')