diff --git a/Gemfile.lock b/Gemfile.lock
index 279f6b3..d88950b 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -8,7 +8,9 @@ GEM
     jwt (2.1.0)
     multipart-post (2.0.0)
     mustermann (1.0.3)
-    puma (3.12.0)
+    nio4r (2.5.8)
+    puma (4.3.12)
+      nio4r (~> 2.0)
     rack (2.0.6)
     rack-protection (2.0.4)
       rack