diff --git a/Gemfile.lock b/Gemfile.lock
index a7ca7c7d..77c616c7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -19,7 +19,7 @@ PATH
       rack (>= 2.2, < 4.0)
       rake (~> 13.0)
       redis (~> 5.0)
-      sinatra (>= 2, < 4)
+      sinatra (>= 2, < 5)
       spicy-proton (~> 2.1)
       statsd-ruby (~> 1.4)
 
@@ -117,10 +117,12 @@ GEM
       nio4r (~> 2.0)
     racc (1.7.1)
     racc (1.7.1-java)
-    rack (2.2.8)
-    rack-protection (3.2.0)
+    rack (3.0.8)
+    rack-protection (4.0.0)
       base64 (>= 0.1.0)
-      rack (~> 2.2, >= 2.2.4)
+      rack (>= 3.0.0, < 4)
+    rack-session (2.0.0)
+      rack (>= 3.0.0)
     rack-test (2.1.0)
       rack (>= 1.3)
     rainbow (3.1.1)
@@ -166,10 +168,11 @@ GEM
       simplecov_json_formatter (~> 0.1)
     simplecov-html (0.12.3)
     simplecov_json_formatter (0.1.4)
-    sinatra (3.2.0)
+    sinatra (4.0.0)
       mustermann (~> 3.0)
-      rack (~> 2.2, >= 2.2.4)
-      rack-protection (= 3.2.0)
+      rack (>= 3.0.0, < 4)
+      rack-protection (= 4.0.0)
+      rack-session (>= 2.0.0, < 3)
       tilt (~> 2.0)
     spicy-proton (2.1.15)
       bindata (~> 2.3)
diff --git a/vmpooler.gemspec b/vmpooler.gemspec
index bc5120c3..48f1b33a 100644
--- a/vmpooler.gemspec
+++ b/vmpooler.gemspec
@@ -33,7 +33,7 @@ Gem::Specification.new do |s|
   s.add_dependency 'rack', '>= 2.2', '< 4.0'
   s.add_dependency 'rake', '~> 13.0'
   s.add_dependency 'redis', '~> 5.0'
-  s.add_dependency 'sinatra', '>= 2', '< 4'
+  s.add_dependency 'sinatra', '>= 2', '< 5'
   s.add_dependency 'spicy-proton', '~> 2.1'
   s.add_dependency 'statsd-ruby', '~> 1.4'