diff --git a/puma-acme.gemspec b/puma-acme.gemspec
index 1ab6a9c..4bb2b22 100644
--- a/puma-acme.gemspec
+++ b/puma-acme.gemspec
@@ -23,7 +23,7 @@ Gem::Specification.new do |s|
 
   s.add_runtime_dependency 'acme-client', '~> 2.0.13'
   s.add_runtime_dependency 'pstore', '~> 0.1'
-  s.add_runtime_dependency 'puma', '~> 6.0'
+  s.add_runtime_dependency 'puma', '>= 6', '< 8'
 
   s.add_development_dependency 'http.rb', '~> 0.12'
   s.add_development_dependency 'minitest', '~> 5.14'