diff --git a/Gemfile.lock b/Gemfile.lock
index 7f41c1e..014eeef 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -62,12 +62,10 @@ GEM
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    thread_safe (0.3.6)
-    tzinfo (1.2.5)
-      thread_safe (~> 0.1)
+    tzinfo (2.0.5)
+      concurrent-ruby (~> 1.0)
     tzinfo-data (1.2018.3)
       tzinfo (>= 1.0.0)
-    wdm (0.1.1)
 
 PLATFORMS
   ruby
@@ -78,7 +76,6 @@ DEPENDENCIES
   jekyll-feed (~> 0.6)
   minima (~> 2.0)
   tzinfo-data
-  wdm (~> 0.1.0)
 
 BUNDLED WITH
    2.1.4