diff --git a/Gemfile.lock b/Gemfile.lock
index c223de6..48fdcb3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -7,7 +7,7 @@ PATH
       puma (~> 6.0)
       redis (~> 5.0)
       sidekiq (~> 7.0)
-      sinatra (>= 2, < 4)
+      sinatra (>= 2, < 5)
       thor (~> 1.0)
       zeitwerk (~> 2.6)
 
@@ -19,6 +19,7 @@ GEM
       i18n (>= 1.6, < 2)
       minitest (>= 5.1)
       tzinfo (~> 2.0)
+    base64 (0.2.0)
     concurrent-ruby (1.2.2)
     connection_pool (2.4.1)
     diff-lcs (1.5.0)
@@ -34,9 +35,12 @@ GEM
     oj (3.14.3)
     puma (6.3.0)
       nio4r (~> 2.0)
-    rack (2.2.7)
-    rack-protection (3.0.6)
-      rack
+    rack (3.1.3)
+    rack-protection (4.0.0)
+      base64 (>= 0.1.0)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
     rack-test (2.1.0)
       rack (>= 1.3)
     redis (5.0.6)
@@ -62,13 +66,14 @@ GEM
       connection_pool (>= 2.3.0)
       rack (>= 2.2.4)
       redis-client (>= 0.14.0)
-    sinatra (3.0.6)
+    sinatra (4.0.0)
       mustermann (~> 3.0)
-      rack (~> 2.2, >= 2.2.4)
-      rack-protection (= 3.0.6)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.0.0)
+      rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
     thor (1.2.2)
-    tilt (2.2.0)
+    tilt (2.3.0)
     tzinfo (2.0.6)
       concurrent-ruby (~> 1.0)
     zeitwerk (2.6.8)
diff --git a/stealth.gemspec b/stealth.gemspec
index 67427d1..2df6665 100644
--- a/stealth.gemspec
+++ b/stealth.gemspec
@@ -17,7 +17,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'puma', '~> 6.0'
   s.add_dependency 'redis', '~> 5.0'
   s.add_dependency 'sidekiq', '~> 7.0'
-  s.add_dependency 'sinatra', '>= 2', '< 4'
+  s.add_dependency 'sinatra', '>= 2', '< 5'
   s.add_dependency 'thor', '~> 1.0'
   s.add_dependency 'zeitwerk', '~> 2.6'