diff --git a/Gemfile.lock b/Gemfile.lock
index e1146d0a..6f884aba 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -91,7 +91,7 @@ GEM
     minitest (5.20.0)
     molinillo (0.8.0)
     mustache (1.1.1)
-    mutex_m (0.1.2)
+    mutex_m (0.2.0)
     nanaimo (0.3.0)
     nap (1.1.0)
     netrc (0.11.0)