diff --git a/Gemfile.lock b/Gemfile.lock
index 0c15513..ce86567 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -105,6 +105,7 @@ GEM
     mime-types (1.18)
     multi_json (1.3.4)
     multi_xml (0.5.1)
+    nio4r (2.5.8)
     nokogiri (1.5.2)
     pg (0.13.2)
     polyglot (0.3.3)
@@ -112,9 +113,9 @@ GEM
       coderay (~> 1.0.5)
       method_source (~> 0.7.1)
       slop (>= 2.4.4, < 3)
-    puma (1.2.2)
-      rack (~> 1.2)
-    rack (1.4.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
+    rack (1.4.7)
     rack-cache (1.2)
       rack (>= 0.4)
     rack-ssl (1.3.2)