diff --git a/api/Gemfile.lock b/api/Gemfile.lock
index 83debe3..f432eed 100644
--- a/api/Gemfile.lock
+++ b/api/Gemfile.lock
@@ -90,6 +90,7 @@ GEM
     minitest (5.7.0)
     multi_json (1.11.0)
     netrc (0.10.3)
+    nio4r (2.3.1)
     nokogiri (1.6.6.2)
       mini_portile (~> 0.6.0)
     parser (2.2.2.3)
@@ -100,9 +101,9 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
-    puma (2.11.3)
-      rack (>= 1.1, < 2.0)
-    rack (1.6.2)
+    puma (4.3.12)
+      nio4r (~> 2.0)
+    rack (1.6.13)
     rack-cors (0.4.0)
     rack-test (0.6.3)
       rack (>= 1.0)