diff --git a/Gemfile.lock b/Gemfile.lock
index fbd6e56..3dcbcc4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -154,6 +154,7 @@ GEM
     net-ssh-gateway (1.2.0)
       net-ssh (>= 2.6.5)
     netrc (0.11.0)
+    nio4r (2.5.7)
     nokogiri (1.8.1)
       mini_portile2 (~> 2.3.0)
     omniauth (1.4.2)
@@ -178,7 +179,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
-    puma (3.11.4)
+    puma (4.3.8)
+      nio4r (~> 2.0)
     quiet_assets (1.0.1)
       railties (~> 3.1)
     rack (1.4.7)