diff --git a/Gemfile.lock b/Gemfile.lock
index 468d861b..5ac04b33 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -198,6 +198,7 @@ GEM
     multipart-post (2.0.0)
     mysql2 (0.4.5)
     netrc (0.11.0)
+    nio4r (2.5.2)
     nokogiri (1.7.0.1)
       mini_portile2 (~> 2.1.0)
     peek (0.2.0)
@@ -222,7 +223,8 @@ GEM
       method_source (~> 0.8.1)
       slop (~> 3.4)
     public_suffix (2.0.5)
-    puma (3.7.1)
+    puma (4.3.1)
+      nio4r (~> 2.0)
     rack (1.6.5)
     rack-test (0.6.3)
       rack (>= 1.0)