diff --git a/cordial.gemspec b/cordial.gemspec
index b300c56..07670db 100644
--- a/cordial.gemspec
+++ b/cordial.gemspec
@@ -19,7 +19,7 @@ Gem::Specification.new do |spec|
   spec.require_paths = ['lib']
 
   spec.add_dependency 'httparty', '~> 0.16'
-  spec.add_dependency 'hashie', '~> 3.5'
+  spec.add_dependency 'hashie', '>= 3.5', '< 5.0'
 
   spec.add_development_dependency 'bundler', '~> 2.0'
   spec.add_development_dependency 'dotenv', '~> 2.4'