diff --git a/varnisher.gemspec b/varnisher.gemspec
index e2766e1..f5a3378 100644
--- a/varnisher.gemspec
+++ b/varnisher.gemspec
@@ -19,9 +19,9 @@ Gem::Specification.new do |s|
   s.executables = ['varnisher']
   s.require_path = 'lib'
 
-  s.add_runtime_dependency 'main', '~> 5.2.0'
-  s.add_runtime_dependency 'nokogiri', '~> 1.6.0'
-  s.add_runtime_dependency 'parallel', '~> 0.8.1'
+  s.add_runtime_dependency 'main', '~> 6.0'
+  s.add_runtime_dependency 'nokogiri', '~> 1.6'
+  s.add_runtime_dependency 'parallel', '~> 1.3'
 
   s.add_development_dependency 'rake', '~> 10.1.0'
   s.add_development_dependency 'minitest', '~> 5.0.6'