diff --git a/sinatra-rdf.gemspec b/sinatra-rdf.gemspec
index 64bab26..104d95c 100755
--- a/sinatra-rdf.gemspec
+++ b/sinatra-rdf.gemspec
@@ -30,7 +30,7 @@ Gem::Specification.new do |gem|
   gem.required_ruby_version      = '>= 3.0'
   gem.requirements               = []
   gem.add_runtime_dependency     'rack-rdf',        '~> 3.3'
-  gem.add_runtime_dependency     'sinatra',         '~> 3.1'
+  gem.add_runtime_dependency     'sinatra',         '~> 4.0'
 
   gem.add_development_dependency 'yard' ,           '~> 0.9'
   gem.add_development_dependency 'rspec',           '~> 3.12'