diff --git a/twingly-url.gemspec b/twingly-url.gemspec
index a81e670..10e1ae1 100644
--- a/twingly-url.gemspec
+++ b/twingly-url.gemspec
@@ -15,7 +15,7 @@ Gem::Specification.new do |s|
   s.required_ruby_version = ">= 2.5"
 
   s.add_dependency "addressable", "~> 2.6"
-  s.add_dependency "public_suffix", ">= 3.0.1", "< 5.0"
+  s.add_dependency "public_suffix", ">= 3.0.1", "< 6.0"
 
   s.add_development_dependency "rake", "~> 12"
   s.add_development_dependency "rspec", "~> 3"