diff --git a/jekyll-theme-hacker.gemspec b/jekyll-theme-hacker.gemspec
index 3ca0642..e59fa4a 100644
--- a/jekyll-theme-hacker.gemspec
+++ b/jekyll-theme-hacker.gemspec
@@ -12,7 +12,7 @@ Gem::Specification.new do |s|
   end
 
   s.platform = Gem::Platform::RUBY
-  s.add_runtime_dependency 'jekyll', '~> 3.5'
+  s.add_runtime_dependency 'jekyll', '> 3.5', '< 5.0'
   s.add_runtime_dependency 'jekyll-seo-tag', '~> 2.0'
   s.add_development_dependency 'html-proofer', '~> 3.0'
   s.add_development_dependency 'rubocop', '~> 0.50'