diff --git a/calendav.gemspec b/calendav.gemspec
index eb2e3bf..463673f 100644
--- a/calendav.gemspec
+++ b/calendav.gemspec
@@ -24,7 +24,7 @@ Gem::Specification.new do |spec|
   spec.executables   = spec.files.grep(%r{^exe/}) { |f| File.basename(f) }
   spec.require_paths = ["lib"]
 
-  spec.add_runtime_dependency "http"
+  spec.add_runtime_dependency "http", "~> 5.0"
   spec.add_runtime_dependency "icalendar"
   spec.add_runtime_dependency "nokogiri"