diff --git a/Gemfile b/Gemfile
index 293602a..a05e934 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,6 @@
 source 'https://rubygems.org'
 
 gem 'sinatra'
+gem 'rackup'
+gem 'puma'
 
diff --git a/Gemfile.lock b/Gemfile.lock
index 474e1b2..c12a3af 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,22 +1,39 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    mustermann (1.0.3)
-    rack (2.0.7)
-    rack-protection (2.0.5)
-      rack
-    sinatra (2.0.5)
-      mustermann (~> 1.0)
-      rack (~> 2.0)
-      rack-protection (= 2.0.5)
+    base64 (0.2.0)
+    logger (1.6.1)
+    mustermann (3.0.3)
+      ruby2_keywords (~> 0.0.1)
+    nio4r (2.7.4)
+    puma (6.5.0)
+      nio4r (~> 2.0)
+    rack (3.1.8)
+    rack-protection (4.1.1)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
+    rackup (2.2.1)
+      rack (>= 3)
+    ruby2_keywords (0.0.5)
+    sinatra (4.1.1)
+      logger (>= 1.6.0)
+      mustermann (~> 3.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.1.1)
+      rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
-    tilt (2.0.9)
+    tilt (2.4.0)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
+  puma
+  rackup
   sinatra
 
 BUNDLED WITH
-   2.0.1
+   2.5.23