diff --git a/Gemfile.lock b/Gemfile.lock
index e3643b6..61900e8 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -180,6 +180,7 @@ GEM
     mini_portile2 (2.0.0)
     minitest (5.9.0)
     multi_json (1.12.1)
+    nio4r (2.5.2)
     nokogiri (1.6.7.2)
       mini_portile2 (~> 2.0.0.rc2)
     orm_adapter (0.5.0)
@@ -193,7 +194,8 @@ GEM
       slop (~> 3.4)
     pry-rails (0.3.4)
       pry (>= 0.9.10)
-    puma (3.4.0)
+    puma (4.3.5)
+      nio4r (~> 2.0)
     rack (1.6.4)
     rack-test (0.6.3)
       rack (>= 1.0)