diff --git a/Gemfile b/Gemfile
index 496c848..6c334c6 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 gem 'activesupport'
-gem 'sinatra'
+gem 'sinatra', '~> 4.1.0'
 
 gem "puma"
 
diff --git a/Gemfile.lock b/Gemfile.lock
index e564d1c..90c3715 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -26,7 +26,7 @@ GEM
     logger (1.7.0)
     method_source (1.1.0)
     minitest (5.25.5)
-    mustermann (2.0.2)
+    mustermann (3.0.4)
       ruby2_keywords (~> 0.0.1)
     nio4r (2.7.4)
     pry (0.15.2)
@@ -37,15 +37,22 @@ GEM
       slop (~> 3.0)
     puma (6.6.1)
       nio4r (~> 2.0)
-    rack (2.2.17)
-    rack-protection (2.2.4)
-      rack
+    rack (3.2.0)
+    rack-protection (4.1.1)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.1.1)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0)
     ruby2_keywords (0.0.5)
     securerandom (0.4.1)
-    sinatra (2.2.4)
-      mustermann (~> 2.0)
-      rack (~> 2.2)
-      rack-protection (= 2.2.4)
+    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)
     slop (3.6.0)
     tilt (2.6.1)
@@ -62,7 +69,7 @@ DEPENDENCIES
   pry
   pry-remote
   puma
-  sinatra
+  sinatra (~> 4.1.0)
 
 BUNDLED WITH
    2.6.2