diff --git a/jekyll.gemspec b/jekyll.gemspec
index 62a866a6..5393e663 100644
--- a/jekyll.gemspec
+++ b/jekyll.gemspec
@@ -28,7 +28,7 @@ Gem::Specification.new do |s|
   s.add_runtime_dependency('listen', "~> 1.3")
   s.add_runtime_dependency('maruku', "~> 0.6.0")
   s.add_runtime_dependency('pygments.rb', "~> 0.5.0")
-  s.add_runtime_dependency('commander', "~> 4.1.3")
+  s.add_runtime_dependency('mercenary', "~> 0.1.0")
   s.add_runtime_dependency('safe_yaml', "~> 0.9.7")
   s.add_runtime_dependency('colorator', "~> 0.1")
   s.add_runtime_dependency('redcarpet', "~> 2.3.0")