diff --git a/Gemfile.lock b/Gemfile.lock
index e438c64..c9e1550 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -195,7 +195,8 @@ GEM
     pry-rails (0.3.9)
       pry (>= 0.10.4)
     public_suffix (3.1.0)
-    puma (3.12.1)
+    puma (4.0.0)
+      nio4r (~> 2.0)
     rack (2.0.7)
     rack-livereload (0.3.17)
       rack