diff --git a/Gemfile b/Gemfile
index 850540b..9ba640c 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,7 +4,7 @@ source 'https://rubygems.org'
 
 # Framework
 gem 'puma', '~> 6.4.2'
-gem 'sinatra', '~> 3.1.0'
+gem 'sinatra', '~> 4.1.0'
 
 # Asset pipeline
 gem 'base64', '~> 0.2.0'
diff --git a/Gemfile.lock b/Gemfile.lock
index 817ee58..89c2980 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -11,12 +11,13 @@ GEM
       rake (>= 13)
     json (2.7.1)
     language_server-protocol (3.17.0.3)
+    logger (1.6.1)
     m (1.6.2)
       method_source (>= 0.6.7)
       rake (>= 0.9.2.2)
     method_source (1.0.0)
     minitest (5.20.0)
-    mustermann (3.0.0)
+    mustermann (3.0.3)
       ruby2_keywords (~> 0.0.1)
     mutex_m (0.2.0)
     nio4r (2.7.0)
@@ -27,9 +28,13 @@ GEM
     puma (6.4.2)
       nio4r (~> 2.0)
     racc (1.7.3)
-    rack (2.2.9)
-    rack-protection (3.1.0)
-      rack (~> 2.2, >= 2.2.4)
+    rack (3.1.8)
+    rack-protection (4.1.0)
+      base64 (>= 0.1.0)
+      logger (>= 1.6.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
     rainbow (3.1.1)
     rake (13.0.6)
     regexp_parser (2.8.3)
@@ -61,16 +66,18 @@ GEM
       rake (>= 13)
     sassc-embedded (1.76.0)
       sass-embedded (~> 1.76)
-    sinatra (3.1.0)
+    sinatra (4.1.0)
+      logger (>= 1.6.0)
       mustermann (~> 3.0)
-      rack (~> 2.2, >= 2.2.4)
-      rack-protection (= 3.1.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.1.0)
+      rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
     sprockets (4.2.1)
       concurrent-ruby (~> 1.0)
       rack (>= 2.2.4, < 4)
     strscan (3.1.0)
-    tilt (2.3.0)
+    tilt (2.4.0)
     uglifier (4.2.0)
       execjs (>= 0.3.0, < 3)
     unicode-display_width (2.5.0)
@@ -89,7 +96,7 @@ DEPENDENCIES
   rubocop-minitest (~> 0.34.2)
   rubocop-performance (~> 1.20)
   sassc-embedded (~> 1.69)
-  sinatra (~> 3.1.0)
+  sinatra (~> 4.1.0)
   sprockets (~> 4.2.1)
   uglifier (~> 4.2.0)