diff --git a/with_advisory_lock.gemspec b/with_advisory_lock.gemspec
index b26a3eb..5c24274 100644
--- a/with_advisory_lock.gemspec
+++ b/with_advisory_lock.gemspec
@@ -19,7 +19,6 @@ Gem::Specification.new do |gem|
   gem.require_paths = %w(lib)
 
   gem.add_runtime_dependency 'activerecord', '>= 3.2'
-  gem.add_runtime_dependency 'thread_safe'
 
   gem.add_development_dependency 'yard'
   gem.add_development_dependency 'minitest'