diff --git a/einhorn.gemspec b/einhorn.gemspec
index f8f0847..d18dc12 100644
--- a/einhorn.gemspec
+++ b/einhorn.gemspec
@@ -25,4 +25,5 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency "minitest", "~> 5"
   gem.add_development_dependency "mocha", "~> 2"
   gem.add_development_dependency "subprocess", "~> 1"
+  gem.add_dependency "fiddle", "~> 1.1"
 end