diff --git a/Gemfile.lock b/Gemfile.lock
index e705e77050..f26fe79476 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -394,7 +394,7 @@ GEM
     multi_json (1.15.0)
     multi_test (1.1.0)
     multi_xml (0.6.0)
-    mutex_m (0.1.2)
+    mutex_m (0.2.0)
     nenv (0.3.0)
     nesty (1.0.2)
     net-imap (0.4.4)