diff --git a/solidus_stock_transfers.gemspec b/solidus_stock_transfers.gemspec
index 345ea40..6059ad8 100644
--- a/solidus_stock_transfers.gemspec
+++ b/solidus_stock_transfers.gemspec
@@ -32,4 +32,5 @@ Gem::Specification.new do |s|
   s.add_development_dependency 'capybara-screenshot'
   s.add_development_dependency 'rspec-activemodel-mocks'
   s.add_development_dependency 'rails-controller-testing'
+  s.add_development_dependency 'puma'
 end