diff --git a/grape-roar.gemspec b/grape-roar.gemspec
index 87b32b5..ce8b357 100644
--- a/grape-roar.gemspec
+++ b/grape-roar.gemspec
@@ -19,6 +19,7 @@ Gem::Specification.new do |gem|
   gem.version       = Grape::Roar::VERSION
 
   gem.add_dependency 'grape'
+  gem.add_dependency 'multi_json'
   gem.add_dependency 'roar', '~> 1.1.0'
   gem.required_ruby_version = '>= 2.1.0'
 end