diff --git a/Gemfile.lock b/Gemfile.lock
index 23b2b38..35da352 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -105,7 +105,8 @@ GEM
       mini_portile2 (~> 2.3.0)
     orm_adapter (0.5.0)
     pg (1.0.0)
-    puma (3.11.4)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     pygments.rb (1.2.1)
       multi_json (>= 1.0.0)
     rack (2.0.5)