diff --git a/Gemfile.lock b/Gemfile.lock
index ecfa27c..e8c6df1 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -44,10 +44,12 @@ GEM
       treetop (~> 1.4.8)
     mime-types (1.25.1)
     multi_json (1.11.2)
+    nio4r (2.5.2)
     pg (0.18.4)
     polyglot (0.3.5)
     power_assert (0.2.7)
-    puma (3.12.4)
+    puma (5.6.7)
+      nio4r (~> 2.0)
     rack (1.4.7)
     rack-cache (1.6.1)
       rack (>= 0.4)