diff --git a/Gemfile.lock b/Gemfile.lock
index e9c2e86..2dc4f3e 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -187,7 +187,8 @@ GEM
     parser (2.3.3.1)
       ast (~> 2.2)
     public_suffix (3.0.3)
-    puma (3.12.2)
+    puma (4.3.3)
+      nio4r (~> 2.0)
     rack (2.0.8)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)