diff --git a/cronofy.gemspec b/cronofy.gemspec
index e4da529..919089c 100644
--- a/cronofy.gemspec
+++ b/cronofy.gemspec
@@ -17,7 +17,7 @@ Gem::Specification.new do |spec|
   spec.files        += Dir['spec/**/*.rb']
   spec.test_files    = Dir['spec/**/*.rb']
 
-  spec.add_runtime_dependency "hashie", ">= 2.1", "< 5"
+  spec.add_runtime_dependency "hashie", ">= 2.1", "< 6"
   spec.add_runtime_dependency "oauth2", ">= 2.0.4"
 
   spec.add_development_dependency "bundler", ">=  1.6", "< 3"