diff --git a/Gemfile.lock b/Gemfile.lock
index d357f68..ac19eb5 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -55,7 +55,8 @@ GEM
       eventmachine (>= 0.12.6)
       rack (>= 1.0.0)
     tilt (1.3.3)
-    tzinfo (0.3.33)
+    tzinfo (2.0.5)
+      concurrent-ruby (~> 1.0)
 
 PLATFORMS
   ruby