diff --git a/Gemfile.lock b/Gemfile.lock
index d901054..f0fd9bd 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -214,7 +214,8 @@ GEM
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
     public_suffix (3.0.1)
-    puma (3.11.0)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.2.2)
     rack-test (0.8.2)
       rack (>= 1.0, < 3)