diff --git a/commonmarker.gemspec b/commonmarker.gemspec
index d1521ece..24340ac7 100644
--- a/commonmarker.gemspec
+++ b/commonmarker.gemspec
@@ -27,7 +27,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'ruby-enum', '~> 0.5'
 
   s.add_development_dependency 'awesome_print'
-  s.add_development_dependency 'json', '~> 1.8'
+  s.add_development_dependency 'json', '~> 2.3'
   s.add_development_dependency 'minitest', '~> 5.6'
   s.add_development_dependency 'minitest-focus', '~> 1.1'
   s.add_development_dependency 'rake'