diff --git a/Gemfile.lock b/Gemfile.lock
index b41dc5b..62fe0cb 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -73,9 +73,10 @@ GEM
     mime-types (2.4.3)
     minitest (5.5.0)
     multi_json (1.10.1)
-    puma (2.10.2)
-      rack (>= 1.1, < 2.0)
-    rack (1.5.2)
+    nio4r (2.5.8)
+    puma (4.3.12)
+      nio4r (~> 2.0)
+    rack (1.5.5)
     rack-test (0.6.2)
       rack (>= 1.0)
     rails (4.1.8)