diff --git a/test/sample_apps/rails4_app/Gemfile b/test/sample_apps/rails4_app/Gemfile
index 12405f3..a6a66fd 100644
--- a/test/sample_apps/rails4_app/Gemfile
+++ b/test/sample_apps/rails4_app/Gemfile
@@ -32,4 +32,4 @@ group :development do
 end
 
 # Use Puma as the app server
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 5.6'
diff --git a/test/sample_apps/rails4_app/Gemfile.lock b/test/sample_apps/rails4_app/Gemfile.lock
index 2b2c938..8ed909a 100644
--- a/test/sample_apps/rails4_app/Gemfile.lock
+++ b/test/sample_apps/rails4_app/Gemfile.lock
@@ -63,9 +63,11 @@ GEM
     mini_portile2 (2.4.0)
     minitest (5.11.3)
     multi_json (1.13.1)
+    nio4r (2.7.0)
     nokogiri (1.9.1)
       mini_portile2 (~> 2.4.0)
-    puma (3.12.0)
+    puma (5.6.8)
+      nio4r (~> 2.0)
     rack (1.6.11)
     rack-test (0.6.3)
       rack (>= 1.0)
@@ -138,7 +140,7 @@ PLATFORMS
 DEPENDENCIES
   byebug
   jbuilder (~> 2.0)
-  puma (~> 3.0)
+  puma (~> 5.6)
   rails (= 4.2.11)
   sass-rails (~> 5.0)
   sdoc (~> 0.4.0)