diff --git a/Gemfile.lock b/Gemfile.lock
index 15f2b94..7a3ecb9 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -112,6 +112,7 @@ GEM
     multi_json (1.12.1)
     netrc (0.11.0)
     newrelic_rpm (3.16.0.318)
+    nio4r (2.5.2)
     nokogiri (1.6.8)
       mini_portile2 (~> 2.1.0)
       pkg-config (~> 1.1.7)
@@ -122,7 +123,8 @@ GEM
       cliver (~> 0.3.1)
       websocket-driver (>= 0.2.0)
     public_suffix (4.0.1)
-    puma (3.5.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     quiet_assets (1.0.3)
       railties (>= 3.1, < 5.0)
     rack (1.6.4)