diff --git a/examples/determinator-rails/Gemfile b/examples/determinator-rails/Gemfile
index 715b0e6..50047d9 100644
--- a/examples/determinator-rails/Gemfile
+++ b/examples/determinator-rails/Gemfile
@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 gem 'rails', '~> 5.1'
-gem 'puma', '~> 3.0'
+gem 'puma', '~> 5.3'
 
 gem 'determinator', path: '../..'
 
diff --git a/examples/determinator-rails/Gemfile.lock b/examples/determinator-rails/Gemfile.lock
index 1878a67..adee8dd 100644
--- a/examples/determinator-rails/Gemfile.lock
+++ b/examples/determinator-rails/Gemfile.lock
@@ -76,14 +76,19 @@ GEM
     marcel (0.3.3)
       mimemagic (~> 0.3.2)
     method_source (1.0.0)
-    mimemagic (0.3.5)
+    mimemagic (0.3.10)
+      nokogiri (~> 1)
+      rake
     mini_mime (1.0.2)
     minitest (5.14.3)
     multipart-post (2.1.1)
     nio4r (2.5.4)
     nokogiri (1.11.1-x86_64-darwin)
       racc (~> 1.4)
-    puma (3.12.6)
+    nokogiri (1.11.1-x86_64-linux)
+      racc (~> 1.4)
+    puma (5.3.1)
+      nio4r (~> 2.0)
     racc (1.5.2)
     rack (2.2.3)
     rack-test (1.1.0)
@@ -132,12 +137,13 @@ GEM
 
 PLATFORMS
   x86_64-darwin-19
+  x86_64-linux
 
 DEPENDENCIES
   byebug
   determinator!
   dotenv-rails
-  puma (~> 3.0)
+  puma (~> 5.3)
   rails (~> 5.1)
 
 BUNDLED WITH