diff --git a/keyless.gemspec b/keyless.gemspec
index 85b5c8f..d6f90fe 100644
--- a/keyless.gemspec
+++ b/keyless.gemspec
@@ -38,6 +38,7 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'activesupport', '>= 6.1'
   spec.add_dependency 'httparty', '>= 0.21'
   spec.add_dependency 'jwt', '~> 2.6'
+  spec.add_dependency 'mutex_m', '~> 0.3.0'
   spec.add_dependency 'recursive-open-struct', '~> 2.0'
   spec.add_dependency 'zeitwerk', '~> 2.6'
 end