diff --git a/Gemfile.lock b/Gemfile.lock
index 66b74f6..caf97db 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -76,7 +76,8 @@ GEM
     parser (2.4.0.0)
       ast (~> 2.2)
     powerpack (0.1.1)
-    puma (3.9.1)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.3)
     rack-test (0.6.3)
       rack (>= 1.0)