diff --git a/rdf-microdata.gemspec b/rdf-microdata.gemspec
index 8c11f99..3281819 100755
--- a/rdf-microdata.gemspec
+++ b/rdf-microdata.gemspec
@@ -31,7 +31,7 @@ Gem::Specification.new do |gem|
   gem.add_runtime_dependency     'rdf-rdfa',        '~> 3.2', '>= 3.2.3'
   gem.add_runtime_dependency     'rdf-xsd',         '~> 3.2', '>= 3.2.1'
   gem.add_runtime_dependency     'htmlentities',    '~> 4.3'
-  gem.add_runtime_dependency     'nokogiri' ,       '~> 1.15', '>= 1.15.3'
+  gem.add_runtime_dependency     'nokogiri' ,       '~> 1.13', '>= 1.13.8'
 
   gem.add_development_dependency 'equivalent-xml' , '~> 0.6'
   gem.add_development_dependency 'yard' ,           '~> 0.9'