diff --git a/implementations/ruby/Gemfile.lock b/implementations/ruby/Gemfile.lock
index 21c0164..7a87cb9 100644
--- a/implementations/ruby/Gemfile.lock
+++ b/implementations/ruby/Gemfile.lock
@@ -8,10 +8,12 @@ GEM
     method_source (0.9.0)
     multipart-post (2.0.0)
     mustermann (1.0.3)
+    nio4r (2.5.8)
     pry (0.11.3)
       coderay (~> 1.1.0)
       method_source (~> 0.9.0)
-    puma (3.11.2)
+    puma (4.3.11)
+      nio4r (~> 2.0)
     rack (2.0.5)
     rack-protection (2.0.4)
       rack