diff --git a/Gemfile b/Gemfile
index 4b42903..96f2a78 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
-gem 'sinatra', '2.0.2'
-gem 'sinatra-contrib', '2.0.2'
+gem 'sinatra', '4.0.0'
+gem 'sinatra-contrib', '4.0.0'
 gem 'rake', '>= 12.3.3'
 gem 'json', '>= 2.3.0'
 gem 'puma', '>= 3.12.4'
diff --git a/Gemfile.lock b/Gemfile.lock
index 790cc50..ec0f247 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -1,35 +1,39 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    backports (2.8.2)
+    base64 (0.2.0)
     httparty (0.14.0)
       multi_xml (>= 0.5.2)
     json (2.3.0)
-    multi_json (1.14.1)
+    multi_json (1.15.0)
     multi_xml (0.6.0)
-    mustermann (1.1.1)
+    mustermann (3.0.3)
       ruby2_keywords (~> 0.0.1)
     nio4r (2.5.2)
     puma (4.3.3)
       nio4r (~> 2.0)
-    rack (2.2.3)
-    rack-protection (2.0.2)
-      rack
+    rack (3.1.14)
+    rack-protection (4.0.0)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.1.1)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0)
     rake (13.0.1)
-    ruby2_keywords (0.0.2)
-    sinatra (2.0.2)
-      mustermann (~> 1.0)
-      rack (~> 2.0)
-      rack-protection (= 2.0.2)
+    ruby2_keywords (0.0.5)
+    sinatra (4.0.0)
+      mustermann (~> 3.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.0.0)
+      rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
-    sinatra-contrib (2.0.2)
-      backports (~> 2.8.2)
-      multi_json
-      mustermann (~> 1.0)
-      rack-protection (= 2.0.2)
-      sinatra (= 2.0.2)
-      tilt (>= 1.3, < 3)
-    tilt (2.0.10)
+    sinatra-contrib (4.0.0)
+      multi_json (>= 0.0.2)
+      mustermann (~> 3.0)
+      rack-protection (= 4.0.0)
+      sinatra (= 4.0.0)
+      tilt (~> 2.0)
+    tilt (2.6.0)
 
 PLATFORMS
   ruby
@@ -40,8 +44,8 @@ DEPENDENCIES
   json (>= 2.3.0)
   puma (>= 3.12.4)
   rake (>= 12.3.3)
-  sinatra (= 2.0.2)
-  sinatra-contrib (= 2.0.2)
+  sinatra (= 4.0.0)
+  sinatra-contrib (= 4.0.0)
 
 BUNDLED WITH
    1.17.3