diff --git a/Gemfile.lock b/Gemfile.lock
index f4f3d7c..5922b34 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -157,12 +157,14 @@ GEM
     mime-types-data (3.2016.0521)
     mini_portile2 (2.1.0)
     multi_json (1.12.1)
+    nio4r (2.5.8)
     nokogiri (1.7.1)
       mini_portile2 (~> 2.1.0)
     parser (2.4.0.0)
       ast (~> 2.2)
     powerpack (0.1.1)
-    puma (3.12.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (1.6.5)
     rack-protection (1.5.3)
       rack