diff --git a/Gemfile.lock b/Gemfile.lock
index 4e3b37f..1cbc28a 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -91,10 +91,9 @@ GEM
       rack-test
       sinatra (~> 1.4.0)
       tilt (>= 1.3, < 3)
-    thread_safe (0.3.6)
     tilt (2.0.8)
-    tzinfo (1.2.5)
-      thread_safe (~> 0.1)
+    tzinfo (2.0.5)
+      concurrent-ruby (~> 1.0)
     tzinfo-data (1.2018.5)
       tzinfo (>= 1.0.0)