diff --git a/Gemfile.lock b/Gemfile.lock
index 4b2b4b0..ada2439 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -11,7 +11,9 @@ GEM
       thor (>= 0.13.6)
     http_accept_language (1.0.2)
     multi_json (1.0.3)
-    puma (3.11.4)
+    nio4r (2.5.8)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (1.6.5)
     rack-contrib (1.1.0)
       rack (>= 0.9.1)