diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d50b717c..da8ecdec 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -20,15 +20,19 @@ jobs:
           - gemfiles/rails61.gemfile
         include:
           - gemfile: gemfiles/rails81.gemfile
-            ruby-version: 3.4.7
+            ruby-version: 4.0.0
+          - gemfile: gemfiles/rails81.gemfile
+            ruby-version: 3.4.8
           - gemfile: gemfiles/rails81.gemfile
             ruby-version: 3.3.10
           - gemfile: gemfiles/rails72.gemfile
-            ruby-version: 3.4.7
+            ruby-version: 4.0.0
+          - gemfile: gemfiles/rails72.gemfile
+            ruby-version: 3.4.8
           - gemfile: gemfiles/rails72.gemfile
             ruby-version: 3.3.10
           - gemfile: gemfiles/rails71.gemfile
-            ruby-version: 3.4.7
+            ruby-version: 3.4.8
           - gemfile: gemfiles/rails71.gemfile
             ruby-version: 3.3.10
           - gemfile: gemfiles/rails70.gemfile
diff --git a/Gemfile b/Gemfile
index 18296292..0575b349 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,6 +1,6 @@
 # This Gemfile is compatible with Ruby 2.5.0 or greater. To test with
 # earlier Rubies, use the appropriate Gemfile from the ./gemfiles/ dir.
-ruby '3.4.7'
+ruby '4.0.0'
 
 source 'https://rubygems.org'
 
@@ -74,6 +74,11 @@ if GEM_VERSION_RAILS < Gem::Version.new('6.0')
 else
   gem 'delayed_job', '~> 4.1', :require => false
 end
+
+gem 'cgi' if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.5.0')
+
+gem 'benchmark' if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+
 gem 'generator_spec'
 gem 'redis', '<= 4.8.0'
 gem 'resque', '< 2.0.0'
diff --git a/gemfiles/rails70.gemfile b/gemfiles/rails70.gemfile
index 7db7c09e..50a19d4b 100644
--- a/gemfiles/rails70.gemfile
+++ b/gemfiles/rails70.gemfile
@@ -6,7 +6,7 @@ is_jruby = defined?(JRUBY_VERSION) || (defined?(RUBY_ENGINE) && RUBY_ENGINE == '
 
 gem 'activerecord-jdbcsqlite3-adapter', :platform => :jruby
 gem 'jruby-openssl', :platform => :jruby
-gem 'rails', '~> 7.0.8'
+gem 'rails', '~> 7.0.10'
 gem 'sqlite3', '~> 1.4', :platform => [:ruby, :mswin, :mingw]
 
 gem 'rspec-rails', '~> 6.0.3'
diff --git a/gemfiles/rails71.gemfile b/gemfiles/rails71.gemfile
index 956c7f16..5df549aa 100644
--- a/gemfiles/rails71.gemfile
+++ b/gemfiles/rails71.gemfile
@@ -6,7 +6,7 @@ is_jruby = defined?(JRUBY_VERSION) || (defined?(RUBY_ENGINE) && RUBY_ENGINE == '
 
 gem 'activerecord-jdbcsqlite3-adapter', :platform => :jruby
 gem 'jruby-openssl', :platform => :jruby
-gem 'rails', '~> 7.1.0'
+gem 'rails', '~> 7.1.6'
 gem 'sqlite3', '~> 1.4', :platform => [:ruby, :mswin, :mingw]
 
 gem 'rspec-rails', '~> 6.0.3'
diff --git a/gemfiles/rails72.gemfile b/gemfiles/rails72.gemfile
index d456165b..e2c5f206 100644
--- a/gemfiles/rails72.gemfile
+++ b/gemfiles/rails72.gemfile
@@ -6,7 +6,7 @@ is_jruby = defined?(JRUBY_VERSION) || (defined?(RUBY_ENGINE) && RUBY_ENGINE == '
 
 gem 'activerecord-jdbcsqlite3-adapter', :platform => :jruby
 gem 'jruby-openssl', :platform => :jruby
-gem 'rails', '~> 7.2.0'
+gem 'rails', '~> 7.2.3'
 gem 'sqlite3', '~> 1.4', :platform => [:ruby, :mswin, :mingw]
 
 gem 'rspec-rails', '~> 6.0.3'
@@ -27,6 +27,10 @@ gem 'sucker_punch', '~> 2.0'
 # We need last sinatra that uses rack 2.x and ruby 2.5.x
 gem 'sinatra', :git => 'https://github.com/sinatra/sinatra', :tag =>'v2.1.0'
 
+gem 'cgi' if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.5.0')
+
+gem 'benchmark' if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+
 gem 'database_cleaner'
 gem 'delayed_job', '4.1.10', :require => false
 gem 'generator_spec'
diff --git a/gemfiles/rails81.gemfile b/gemfiles/rails81.gemfile
index ded7bbd9..96286207 100644
--- a/gemfiles/rails81.gemfile
+++ b/gemfiles/rails81.gemfile
@@ -6,7 +6,7 @@ is_jruby = defined?(JRUBY_VERSION) || (defined?(RUBY_ENGINE) && RUBY_ENGINE == '
 
 gem 'activerecord-jdbcsqlite3-adapter', :platform => :jruby
 gem 'jruby-openssl', :platform => :jruby
-gem 'rails', '~> 8.1.0'
+gem 'rails', '~> 8.1.1'
 gem 'sqlite3', '~> 2.1', :platform => [:ruby, :mswin, :mingw]
 
 gem 'rspec-rails', '~> 6.0.3'
@@ -27,6 +27,10 @@ gem 'sucker_punch', '~> 2.0'
 # We need last sinatra that uses rack 2.x and ruby 2.5.x
 gem 'sinatra', :git => 'https://github.com/sinatra/sinatra', :tag =>'v2.1.0'
 
+gem 'cgi' if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.5.0')
+
+gem 'benchmark' if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+
 gem 'database_cleaner'
 gem 'delayed_job', '4.1.13', :require => false
 gem 'generator_spec'
diff --git a/spec/controllers/home_controller_spec.rb b/spec/controllers/home_controller_spec.rb
index 7086dcd8..d367c362 100644
--- a/spec/controllers/home_controller_spec.rb
+++ b/spec/controllers/home_controller_spec.rb
@@ -446,17 +446,29 @@ def send_req(meth, path, args)
         else
           expect(frames[-2][:method]).to be_eql('tap')
         end
-        if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0')
+        if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+          expect(frames[-2][:locals]).to be_eql(locals[1])
+        elsif Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0')
           expect(frames[-2][:locals]).to be_nil
         else
           expect(frames[-2][:locals]).to be_eql(locals[1])
         end
 
-        expect(frames[-3][:locals]).to be_eql(locals[2])
-        expect(frames[-4][:locals]).to be_eql(locals[3])
-        # Frames: -5 (and -6 in rails < 8.0) are not app frames, and have different
-        # contents in different Ruby versions.
-        if Gem::Version.new(Rails.version) >= Gem::Version.new('8.0.0')
+        if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+          expect(frames[-3][:locals]).to be_eql(locals[3])
+        else
+          expect(frames[-3][:locals]).to be_eql(locals[2])
+          expect(frames[-4][:locals]).to be_eql(locals[3])
+        end
+
+        # Skip non-app frames, which vary based on Ruby and Rails versions
+        if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+          if Gem::Version.new(Rails.version) >= Gem::Version.new('8.0.0')
+            expect(frames[-5][:locals]).to be_eql(locals[4])
+          else
+            expect(frames[-4][:locals]).to be_eql(locals[4])
+          end
+        elsif Gem::Version.new(Rails.version) >= Gem::Version.new('8.0.0')
           expect(frames[-6][:locals]).to be_eql(locals[4])
         else
           expect(frames[-7][:locals]).to be_eql(locals[4])
diff --git a/spec/rollbar/middleware/sinatra_spec.rb b/spec/rollbar/middleware/sinatra_spec.rb
index 9913570c..fcae62d4 100644
--- a/spec/rollbar/middleware/sinatra_spec.rb
+++ b/spec/rollbar/middleware/sinatra_spec.rb
@@ -293,17 +293,29 @@ def app
           else
             expect(frames[-2][:method]).to be_eql('tap')
           end
-          if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0')
+          if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+            expect(frames[-2][:locals]).to be_eql(locals[1])
+          elsif Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('3.0.0')
             expect(frames[-2][:locals]).to be_nil
           else
             expect(frames[-2][:locals]).to be_eql(locals[1])
           end
 
-          expect(frames[-3][:locals]).to be_eql(locals[2])
-          expect(frames[-4][:locals]).to be_eql(locals[3])
-          # Frames: -5 (and -6 in rails < 8.0) are not app frames, and have different
-          # contents in different Ruby versions.
-          if Gem::Version.new(Rails.version) >= Gem::Version.new('8.0.0')
+          if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+            expect(frames[-3][:locals]).to be_eql(locals[3])
+          else
+            expect(frames[-3][:locals]).to be_eql(locals[2])
+            expect(frames[-4][:locals]).to be_eql(locals[3])
+          end
+
+          # Skip non-app frames, which vary based on Ruby and Rails versions
+          if Gem::Version.new(RUBY_VERSION) >= Gem::Version.new('4.0.0')
+            if Gem::Version.new(Rails.version) >= Gem::Version.new('8.0.0')
+              expect(frames[-5][:locals]).to be_eql(locals[4])
+            else
+              expect(frames[-4][:locals]).to be_eql(locals[4])
+            end
+          elsif Gem::Version.new(Rails.version) >= Gem::Version.new('8.0.0')
             expect(frames[-6][:locals]).to be_eql(locals[4])
           else
             expect(frames[-7][:locals]).to be_eql(locals[4])
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index a81c1cdf..1985812b 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -1,9 +1,9 @@
 begin
   require 'simplecov'
 
-  SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter[
+  SimpleCov.formatter = SimpleCov::Formatter::MultiFormatter.new(
     SimpleCov::Formatter::HTMLFormatter
-  ]
+  )
 
   SimpleCov.start do
     add_filter '/spec/'