diff --git a/jekyll-commonmark-ghpages.gemspec b/jekyll-commonmark-ghpages.gemspec
index 0a4739c..a82aa3b 100644
--- a/jekyll-commonmark-ghpages.gemspec
+++ b/jekyll-commonmark-ghpages.gemspec
@@ -16,7 +16,7 @@ Gem::Specification.new do |spec|
 
   spec.add_runtime_dependency "jekyll", ">= 3.9", "< 4.0"
   spec.add_runtime_dependency "jekyll-commonmark", "~> 1.4.0"
-  spec.add_runtime_dependency "commonmarker", ">= 0.23.7", "< 1.2.0"
+  spec.add_runtime_dependency "commonmarker", ">= 0.23.7", "< 2.1.0"
   spec.add_runtime_dependency "rouge", ">= 2.0", "< 5.0"
 
   spec.add_development_dependency "rspec", "~> 3.0"