diff --git a/spec/lib/appsignal/cli/install_spec.rb b/spec/lib/appsignal/cli/install_spec.rb
index 2e6c7fde..ff64b320 100644
--- a/spec/lib/appsignal/cli/install_spec.rb
+++ b/spec/lib/appsignal/cli/install_spec.rb
@@ -631,7 +631,6 @@ def run
           it "completes the installation" do
             run
 
-            puts output
             expect(output).to include(*installation_instructions)
             expect(output).to include_complete_install
           end
diff --git a/spec/lib/appsignal/hooks/activejob_spec.rb b/spec/lib/appsignal/hooks/activejob_spec.rb
index 493d9cc9..d9c84fd7 100644
--- a/spec/lib/appsignal/hooks/activejob_spec.rb
+++ b/spec/lib/appsignal/hooks/activejob_spec.rb
@@ -76,39 +76,33 @@
       ActiveJob::Base.queue_adapter = :inline
 
       start_agent(:options => options)
-      class ActiveJobTestJob < ActiveJob::Base
+      stub_const("ActiveJobTestJob", Class.new(ActiveJob::Base) do
         def perform(*_args)
         end
-      end
+      end)
 
-      class ActiveJobErrorTestJob < ActiveJob::Base
+      stub_const("ActiveJobErrorTestJob", Class.new(ActiveJob::Base) do
         def perform
           raise "uh oh"
         end
-      end
+      end)
 
-      class ActiveJobErrorWithRetryTestJob < ActiveJob::Base
+      stub_const("ActiveJobErrorWithRetryTestJob", Class.new(ActiveJob::Base) do
         retry_on StandardError, :wait => 0.seconds, :attempts => 2
 
         def perform
           raise "uh oh"
         end
-      end
+      end)
 
-      class ActiveJobCustomQueueTestJob < ActiveJob::Base
+      stub_const("ActiveJobCustomQueueTestJob", Class.new(ActiveJob::Base) do
         queue_as :custom_queue
 
         def perform(*_args)
         end
-      end
+      end)
     end
     around { |example| keep_transactions { example.run } }
-    after do
-      Object.send(:remove_const, :ActiveJobTestJob)
-      Object.send(:remove_const, :ActiveJobErrorTestJob)
-      Object.send(:remove_const, :ActiveJobErrorWithRetryTestJob)
-      Object.send(:remove_const, :ActiveJobCustomQueueTestJob)
-    end
 
     it "reports the name from the ActiveJob integration" do
       tags = { :queue => queue }
@@ -149,15 +143,12 @@ def perform(*_args)
     if DependencyHelper.rails_version >= Gem::Version.new("5.0.0")
       context "with priority" do
         before do
-          class ActiveJobPriorityTestJob < ActiveJob::Base
+          stub_const("ActiveJobPriorityTestJob", Class.new(ActiveJob::Base) do
             queue_with_priority 10
 
             def perform(*_args)
             end
-          end
-        end
-        after do
-          Object.send(:remove_const, :ActiveJobPriorityTestJob)
+          end)
         end
 
         it "reports the priority as tag on the transaction" do
@@ -264,16 +255,13 @@ def perform(*_args)
       if DependencyHelper.rails_version >= Gem::Version.new("5.0.0")
         context "with priority" do
           before do
-            class ActiveJobErrorPriorityTestJob < ActiveJob::Base
+            stub_const("ActiveJobErrorPriorityTestJob", Class.new(ActiveJob::Base) do
               queue_with_priority 10
 
               def perform(*_args)
                 raise "uh oh"
               end
-            end
-          end
-          after do
-            Object.send(:remove_const, :ActiveJobErrorPriorityTestJob)
+            end)
           end
 
           it "reports the priority as tag on the transaction" do
@@ -370,31 +358,28 @@ def perform(*_args)
     context "with provider_job_id",
       :skip => DependencyHelper.rails_version < Gem::Version.new("5.0.0") do
       before do
-        module ActiveJob
-          module QueueAdapters
+        stub_const(
+          "ActiveJob::QueueAdapters::AppsignalTestAdapter",
+          Class.new(ActiveJob::QueueAdapters::InlineAdapter) do
             # Adapter used in our test suite to add provider data to the job
             # data, as is done by Rails provided ActiveJob adapters.
             #
             # This implementation is based on the
             # `ActiveJob::QueueAdapters::InlineAdapter`.
-            class AppsignalTestAdapter < InlineAdapter
-              def enqueue(job)
-                Base.execute(job.serialize.merge("provider_job_id" => "my_provider_job_id"))
-              end
+            def enqueue(job)
+              ActiveJob::Base.execute(
+                job.serialize.merge("provider_job_id" => "my_provider_job_id")
+              )
             end
           end
-        end
+        )
 
-        class ProviderWrappedActiveJobTestJob < ActiveJob::Base
+        stub_const("ProviderWrappedActiveJobTestJob", Class.new(ActiveJob::Base) do
           self.queue_adapter = :appsignal_test
 
           def perform(*_args)
           end
-        end
-      end
-      after do
-        ActiveJob::QueueAdapters.send(:remove_const, :AppsignalTestAdapter)
-        Object.send(:remove_const, :ProviderWrappedActiveJobTestJob)
+        end)
       end
 
       it "sets provider_job_id as tag" do
@@ -409,31 +394,26 @@ def perform(*_args)
     context "with enqueued_at",
       :skip => DependencyHelper.rails_version < Gem::Version.new("6.0.0") do
       before do
-        module ActiveJob
-          module QueueAdapters
+        stub_const(
+          "ActiveJob::QueueAdapters::AppsignalTestAdapter",
+          Class.new(ActiveJob::QueueAdapters::InlineAdapter) do
             # Adapter used in our test suite to add provider data to the job
             # data, as is done by Rails provided ActiveJob adapters.
             #
             # This implementation is based on the
             # `ActiveJob::QueueAdapters::InlineAdapter`.
-            class AppsignalTestAdapter < InlineAdapter
-              def enqueue(job)
-                Base.execute(job.serialize.merge("enqueued_at" => "2020-10-10T10:10:10Z"))
-              end
+            def enqueue(job)
+              ActiveJob::Base.execute(job.serialize.merge("enqueued_at" => "2020-10-10T10:10:10Z"))
             end
           end
-        end
+        )
 
-        class ProviderWrappedActiveJobTestJob < ActiveJob::Base
+        stub_const("ProviderWrappedActiveJobTestJob", Class.new(ActiveJob::Base) do
           self.queue_adapter = :appsignal_test
 
           def perform(*_args)
           end
-        end
-      end
-      after do
-        ActiveJob::QueueAdapters.send(:remove_const, :AppsignalTestAdapter)
-        Object.send(:remove_const, :ProviderWrappedActiveJobTestJob)
+        end)
       end
 
       it "sets queue time on transaction" do
@@ -448,13 +428,10 @@ def perform(*_args)
       include ActionMailerHelpers
 
       before do
-        class ActionMailerTestJob < ActionMailer::Base
+        stub_const("ActionMailerTestJob", Class.new(ActionMailer::Base) do
           def welcome(_first_arg = nil, _second_arg = nil)
           end
-        end
-      end
-      after do
-        Object.send(:remove_const, :ActionMailerTestJob)
+        end)
       end
 
       context "without params" do
@@ -524,15 +501,12 @@ def welcome(_first_arg = nil, _second_arg = nil)
         include ActionMailerHelpers
 
         before do
-          class ActionMailerTestMailDeliveryJob < ActionMailer::Base
+          stub_const("ActionMailerTestMailDeliveryJob", Class.new(ActionMailer::Base) do
             self.delivery_job = ActionMailer::MailDeliveryJob
 
             def welcome(*_args)
             end
-          end
-        end
-        after do
-          Object.send(:remove_const, :ActionMailerTestMailDeliveryJob)
+          end)
         end
 
         it "sets the Action mailer data on the transaction" do
diff --git a/spec/lib/appsignal/hooks/celluloid_spec.rb b/spec/lib/appsignal/hooks/celluloid_spec.rb
index 855d2ab7..2dab49b8 100644
--- a/spec/lib/appsignal/hooks/celluloid_spec.rb
+++ b/spec/lib/appsignal/hooks/celluloid_spec.rb
@@ -1,7 +1,7 @@
 describe Appsignal::Hooks::CelluloidHook do
   context "with celluloid" do
-    before :context do
-      module Celluloid
+    before do
+      stub_const("Celluloid", Module.new do
         def self.shutdown
           @shut_down = true
         end
@@ -9,12 +9,9 @@ def self.shutdown
         def self.shut_down?
           @shut_down == true
         end
-      end
+      end)
       Appsignal::Hooks::CelluloidHook.new.install
     end
-    after :context do
-      Object.send(:remove_const, :Celluloid)
-    end
 
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
@@ -22,11 +19,12 @@ def self.shut_down?
       it { is_expected.to be_truthy }
     end
 
-    specify { expect(Appsignal).to receive(:stop) }
-    specify { expect(Celluloid.shut_down?).to be true }
-
-    after do
-      Celluloid.shutdown
+    describe "#install" do
+      it "calls Appsignal.stop on shutdown" do
+        expect(Appsignal).to receive(:stop)
+        Celluloid.shutdown
+        expect(Celluloid.shut_down?).to be true
+      end
     end
   end
 
diff --git a/spec/lib/appsignal/hooks/data_mapper_spec.rb b/spec/lib/appsignal/hooks/data_mapper_spec.rb
index 022191a1..dcf833ab 100644
--- a/spec/lib/appsignal/hooks/data_mapper_spec.rb
+++ b/spec/lib/appsignal/hooks/data_mapper_spec.rb
@@ -1,21 +1,12 @@
 describe Appsignal::Hooks::DataMapperHook do
   context "with datamapper" do
-    before :context do
-      module DataMapper
-      end
-
-      module DataObjects
-        class Connection
-        end
-      end
+    before do
+      stub_const("DataMapper", Module.new)
+      stub_const("DataObjects", Module.new)
+      stub_const("DataObjects::Connection", Class.new)
       Appsignal::Hooks::DataMapperHook.new.install
     end
 
-    after :context do
-      Object.send(:remove_const, :DataMapper)
-      Object.send(:remove_const, :DataObjects)
-    end
-
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
 
diff --git a/spec/lib/appsignal/hooks/delayed_job_spec.rb b/spec/lib/appsignal/hooks/delayed_job_spec.rb
index 117b93c4..dbd0597a 100644
--- a/spec/lib/appsignal/hooks/delayed_job_spec.rb
+++ b/spec/lib/appsignal/hooks/delayed_job_spec.rb
@@ -1,21 +1,17 @@
 describe Appsignal::Hooks::DelayedJobHook do
   context "with delayed job" do
-    before(:context) do
-      module Delayed
-        class Plugin
-          def self.callbacks
-          end
+    before do
+      stub_const("Delayed::Plugin", Class.new do
+        def self.callbacks
         end
-
-        class Worker
-          def self.plugins
-            @plugins ||= []
-          end
+      end)
+      stub_const("Delayed::Worker", Class.new do
+        def self.plugins
+          @plugins ||= []
         end
-      end
+      end)
+      start_agent
     end
-    after(:context) { Object.send(:remove_const, :Delayed) }
-    before { start_agent }
 
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
diff --git a/spec/lib/appsignal/hooks/excon_spec.rb b/spec/lib/appsignal/hooks/excon_spec.rb
index ac8de6e5..07160aa9 100644
--- a/spec/lib/appsignal/hooks/excon_spec.rb
+++ b/spec/lib/appsignal/hooks/excon_spec.rb
@@ -2,15 +2,14 @@
   before { start_agent }
 
   context "with Excon" do
-    before(:context) do
-      class Excon
+    before do
+      stub_const("Excon", Class.new do
         def self.defaults
           @defaults ||= {}
         end
-      end
+      end)
       Appsignal::Hooks::ExconHook.new.install
     end
-    after(:context) { Object.send(:remove_const, :Excon) }
 
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
diff --git a/spec/lib/appsignal/hooks/gvl_spec.rb b/spec/lib/appsignal/hooks/gvl_spec.rb
index b9fd5499..b5c1d427 100644
--- a/spec/lib/appsignal/hooks/gvl_spec.rb
+++ b/spec/lib/appsignal/hooks/gvl_spec.rb
@@ -32,14 +32,10 @@ def expect_gvltools_require
     end
 
     context "with old versions of GVLTools" do
-      before(:context) do
-        module GVLTools
-          VERSION = "0.1.0".freeze
-        end
+      before do
+        stub_const("GVLTools::VERSION", "0.1.0")
       end
 
-      after(:context) { Object.send(:remove_const, :GVLTools) }
-
       before(:each) { expect_gvltools_require }
 
       describe "#dependencies_present?" do
@@ -50,24 +46,19 @@ module GVLTools
     end
 
     context "with new versions of GVLTools" do
-      before(:context) do
-        module GVLTools
-          VERSION = "0.2.0".freeze
-
-          module GlobalTimer
-            def self.enable
-            end
+      before do
+        stub_const("GVLTools", Module.new)
+        stub_const("GVLTools::VERSION", "0.2.0")
+        stub_const("GVLTools::GlobalTimer", Module.new do
+          def self.enable
           end
-
-          module WaitingThreads
-            def self.enable
-            end
+        end)
+        stub_const("GVLTools::WaitingThreads", Module.new do
+          def self.enable
           end
-        end
+        end)
       end
 
-      after(:context) { Object.send(:remove_const, :GVLTools) }
-
       describe "#dependencies_present?" do
         before(:each) { expect_gvltools_require }
 
diff --git a/spec/lib/appsignal/hooks/mongo_ruby_driver_spec.rb b/spec/lib/appsignal/hooks/mongo_ruby_driver_spec.rb
index 67f56ced..13732dbb 100644
--- a/spec/lib/appsignal/hooks/mongo_ruby_driver_spec.rb
+++ b/spec/lib/appsignal/hooks/mongo_ruby_driver_spec.rb
@@ -7,19 +7,14 @@
       allow(Appsignal::Hooks::MongoMonitorSubscriber).to receive(:new).and_return(subscriber)
     end
 
-    before(:context) do
-      module Mongo
-        module Monitoring
-          COMMAND = "command".freeze
-
-          class Global
-            def subscribe
-            end
-          end
+    before do
+      stub_const("Mongo::Monitoring", Module.new)
+      stub_const("Mongo::Monitoring::COMMAND", "command")
+      stub_const("Mongo::Monitoring::Global", Class.new do
+        def subscribe
         end
-      end
+      end)
     end
-    after(:context) { Object.send(:remove_const, :Mongo) }
 
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
diff --git a/spec/lib/appsignal/hooks/passenger_spec.rb b/spec/lib/appsignal/hooks/passenger_spec.rb
index 6bf96052..10e6f542 100644
--- a/spec/lib/appsignal/hooks/passenger_spec.rb
+++ b/spec/lib/appsignal/hooks/passenger_spec.rb
@@ -1,10 +1,8 @@
 describe Appsignal::Hooks::PassengerHook do
   context "with passenger" do
-    before(:context) do
-      module PhusionPassenger
-      end
+    before do
+      stub_const("PhusionPassenger", Module.new)
     end
-    after(:context) { Object.send(:remove_const, :PhusionPassenger) }
 
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
diff --git a/spec/lib/appsignal/hooks/shoryuken_spec.rb b/spec/lib/appsignal/hooks/shoryuken_spec.rb
index fd53e552..d06d2c5e 100644
--- a/spec/lib/appsignal/hooks/shoryuken_spec.rb
+++ b/spec/lib/appsignal/hooks/shoryuken_spec.rb
@@ -1,17 +1,13 @@
 describe Appsignal::Hooks::ShoryukenHook do
   context "with shoryuken" do
-    before(:context) do
-      module Shoryuken
+    before do
+      stub_const("Shoryuken", Module.new do
         def self.configure_server
         end
-      end
+      end)
       Appsignal::Hooks::ShoryukenHook.new.install
     end
 
-    after(:context) do
-      Object.send(:remove_const, :Shoryuken)
-    end
-
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
 
diff --git a/spec/lib/appsignal/hooks/unicorn_spec.rb b/spec/lib/appsignal/hooks/unicorn_spec.rb
index 35d3ae93..cbd761c7 100644
--- a/spec/lib/appsignal/hooks/unicorn_spec.rb
+++ b/spec/lib/appsignal/hooks/unicorn_spec.rb
@@ -1,30 +1,27 @@
 describe Appsignal::Hooks::UnicornHook do
   context "with unicorn" do
-    before :context do
-      module Unicorn
-        class HttpServer
-          def worker_loop(_worker)
-            @worker_loop = true
-          end
-
-          def worker_loop?
-            @worker_loop == true
-          end
+    before do
+      stub_const("Unicorn", Module.new)
+      stub_const("Unicorn::HttpServer", Class.new do
+        def worker_loop(_worker)
+          @worker_loop = true
         end
 
-        class Worker
-          def close
-            @close = true
-          end
+        def worker_loop?
+          @worker_loop == true
+        end
+      end)
+      stub_const("Unicorn::Worker", Class.new do
+        def close
+          @close = true
+        end
 
-          def close?
-            @close == true
-          end
+        def close?
+          @close == true
         end
-      end
+      end)
       Appsignal::Hooks::UnicornHook.new.install
     end
-    after(:context) { Object.send(:remove_const, :Unicorn) }
 
     describe "#dependencies_present?" do
       subject { described_class.new.dependencies_present? }
diff --git a/spec/lib/appsignal/integrations/data_mapper_spec.rb b/spec/lib/appsignal/integrations/data_mapper_spec.rb
index 1e4de9e7..0b0fd58e 100644
--- a/spec/lib/appsignal/integrations/data_mapper_spec.rb
+++ b/spec/lib/appsignal/integrations/data_mapper_spec.rb
@@ -1,11 +1,6 @@
 require "appsignal/integrations/data_mapper"
 
 describe Appsignal::Hooks::DataMapperLogListener do
-  module DataMapperLog
-    def log(message)
-    end
-  end
-
   describe "#log" do
     let(:transaction) { http_request_transaction }
     let(:message) do
@@ -14,17 +9,12 @@ def log(message)
         :duration => 100_000_000 # nanoseconds
       )
     end
-    let(:connection_class) do
-      module DataObjects
-        module Sqlite3
-          class Connection
-            include DataMapperLog
-            include Appsignal::Hooks::DataMapperLogListener
-          end
-        end
-      end
-    end
     before do
+      stub_const("DataMapperLog", Module.new do
+        def log(message)
+        end
+      end)
+      stub_const("DataObjects", Module.new)
       start_agent
       set_current_transaction(transaction)
     end
@@ -34,28 +24,35 @@ def log_message
       connection_class.new.log(message)
     end
 
-    it "records the log entry in an event" do
-      log_message
+    context "when the scheme is SQL-like" do
+      let(:connection_class) { DataObjects::Sqlite3::Connection }
+      before do
+        stub_const("DataObjects::Sqlite3::Connection", Class.new do
+          include DataMapperLog
+          include Appsignal::Hooks::DataMapperLogListener
+        end)
+      end
 
-      expect(transaction).to include_event(
-        "name" => "query.data_mapper",
-        "title" => "DataMapper Query",
-        "body" => "SELECT * from users",
-        "body_format" => Appsignal::EventFormatter::SQL_BODY_FORMAT,
-        "duration" => 100.0
-      )
+      it "records the log entry in an event" do
+        log_message
+
+        expect(transaction).to include_event(
+          "name" => "query.data_mapper",
+          "title" => "DataMapper Query",
+          "body" => "SELECT * from users",
+          "body_format" => Appsignal::EventFormatter::SQL_BODY_FORMAT,
+          "duration" => 100.0
+        )
+      end
     end
 
-    context "when the scheme is not sql-like" do
-      let(:connection_class) do
-        module DataObjects
-          module MongoDB
-            class Connection
-              include DataMapperLog
-              include Appsignal::Hooks::DataMapperLogListener
-            end
-          end
-        end
+    context "when the scheme is not SQL-like" do
+      let(:connection_class) { DataObjects::MongoDB::Connection }
+      before do
+        stub_const("DataObjects::MongoDB::Connection", Class.new do
+          include DataMapperLog
+          include Appsignal::Hooks::DataMapperLogListener
+        end)
       end
 
       it "records the log entry in an event without body" do
diff --git a/spec/lib/appsignal/integrations/delayed_job_plugin_spec.rb b/spec/lib/appsignal/integrations/delayed_job_plugin_spec.rb
index 29144d9d..19e9ee22 100644
--- a/spec/lib/appsignal/integrations/delayed_job_plugin_spec.rb
+++ b/spec/lib/appsignal/integrations/delayed_job_plugin_spec.rb
@@ -1,22 +1,19 @@
 describe "Appsignal::Integrations::DelayedJobHook" do
-  before(:context) do
-    module Delayed
-      class Plugin
-        def self.callbacks
-        end
+  let(:options) { {} }
+  before do
+    stub_const("Delayed", Module.new)
+    stub_const("Delayed::Plugin", Class.new do
+      def self.callbacks
       end
-
-      class Worker
-        def self.plugins
-          @plugins ||= []
-        end
+    end)
+    stub_const("Delayed::Worker", Class.new do
+      def self.plugins
+        @plugins ||= []
       end
-    end
+    end)
     require "appsignal/integrations/delayed_job_plugin"
+    start_agent(:options => options)
   end
-  after(:context) { Object.send(:remove_const, :Delayed) }
-  let(:options) { {} }
-  before { start_agent(:options => options) }
 
   # We haven't found a way to test the hooks, we'll have to do that manually
 
diff --git a/spec/lib/appsignal/integrations/object_spec.rb b/spec/lib/appsignal/integrations/object_spec.rb
index 3016bfca..a8a27d12 100644
--- a/spec/lib/appsignal/integrations/object_spec.rb
+++ b/spec/lib/appsignal/integrations/object_spec.rb
@@ -87,14 +87,13 @@ def splat(*args, **kwargs)
 
         context "with named class" do
           before do
-            class NamedClass
+            stub_const("NamedClass", Class.new do
               def foo
                 1
               end
               appsignal_instrument_method :foo
-            end
+            end)
           end
-          after { Object.send(:remove_const, :NamedClass) }
           let(:klass) { NamedClass }
 
           it "instruments the method and calls it" do
@@ -106,18 +105,13 @@ def foo
 
         context "with nested named class" do
           before do
-            module MyModule
-              module NestedModule
-                class NamedClass
-                  def bar
-                    2
-                  end
-                  appsignal_instrument_method :bar
-                end
+            stub_const("MyModule::NestedModule::NamedClass", Class.new do
+              def bar
+                2
               end
-            end
+              appsignal_instrument_method :bar
+            end)
           end
-          after { Object.send(:remove_const, :MyModule) }
           let(:klass) { MyModule::NestedModule::NamedClass }
 
           it "instruments the method and calls it" do
@@ -257,14 +251,13 @@ def self.splat(*args, **kwargs)
 
         context "with named class" do
           before do
-            class NamedClass
+            stub_const("NamedClass", Class.new do
               def self.bar
                 2
               end
               appsignal_instrument_class_method :bar
-            end
+            end)
           end
-          after { Object.send(:remove_const, :NamedClass) }
           let(:klass) { NamedClass }
 
           it "instruments the method and calls it" do
@@ -276,18 +269,13 @@ def self.bar
 
           context "with nested named class" do
             before do
-              module MyModule
-                module NestedModule
-                  class NamedClass
-                    def self.bar
-                      2
-                    end
-                    appsignal_instrument_class_method :bar
-                  end
+              stub_const("MyModule::NestedModule::NamedClass", Class.new do
+                def self.bar
+                  2
                 end
-              end
+                appsignal_instrument_class_method :bar
+              end)
             end
-            after { Object.send(:remove_const, :MyModule) }
             let(:klass) { MyModule::NestedModule::NamedClass }
 
             it "instruments the method and calls it" do
diff --git a/spec/lib/appsignal/integrations/resque_spec.rb b/spec/lib/appsignal/integrations/resque_spec.rb
index ec4397ac..df5da1c9 100644
--- a/spec/lib/appsignal/integrations/resque_spec.rb
+++ b/spec/lib/appsignal/integrations/resque_spec.rb
@@ -14,26 +14,22 @@ def perform_rescue_job(klass, options = {})
     before do
       start_agent(:options => options)
 
-      class ResqueTestJob
+      stub_const("ResqueTestJob", Class.new do
         def self.perform(*_args)
         end
-      end
+      end)
 
-      class ResqueErrorTestJob
+      stub_const("ResqueErrorTestJob", Class.new do
         def self.perform
           raise "resque job error"
         end
-      end
+      end)
 
       expect(Appsignal).to receive(:stop) # Resque calls stop after every job
     end
     around do |example|
       keep_transactions { example.run }
     end
-    after do
-      Object.send(:remove_const, :ResqueTestJob)
-      Object.send(:remove_const, :ResqueErrorTestJob)
-    end
 
     it "tracks a transaction on perform" do
       perform_rescue_job(ResqueTestJob)
diff --git a/spec/lib/appsignal/integrations/sidekiq_spec.rb b/spec/lib/appsignal/integrations/sidekiq_spec.rb
index 0c5ddb7d..b9329290 100644
--- a/spec/lib/appsignal/integrations/sidekiq_spec.rb
+++ b/spec/lib/appsignal/integrations/sidekiq_spec.rb
@@ -526,20 +526,20 @@ def expect_transaction_to_have_sidekiq_event(transaction)
       Appsignal.internal_logger = test_logger(log)
       ActiveJob::Base.queue_adapter = :sidekiq
 
-      class ActiveJobSidekiqTestJob < ActiveJob::Base
+      stub_const("ActiveJobSidekiqTestJob", Class.new(ActiveJob::Base) do
         self.queue_adapter = :sidekiq
 
         def perform(*_args)
         end
-      end
+      end)
 
-      class ActiveJobSidekiqErrorTestJob < ActiveJob::Base
+      stub_const("ActiveJobSidekiqErrorTestJob", Class.new(ActiveJob::Base) do
         self.queue_adapter = :sidekiq
 
         def perform(*_args)
           raise "uh oh"
         end
-      end
+      end)
       # Manually add the AppSignal middleware for the Testing environment.
       # It doesn't use configured middlewares by default looks like.
       # We test somewhere else if the middleware is installed properly.
@@ -547,10 +547,6 @@ def perform(*_args)
         chain.add Appsignal::Integrations::SidekiqMiddleware
       end
     end
-    after do
-      Object.send(:remove_const, :ActiveJobSidekiqTestJob)
-      Object.send(:remove_const, :ActiveJobSidekiqErrorTestJob)
-    end
 
     it "reports the transaction from the ActiveJob integration" do
       perform_sidekiq_job(ActiveJobSidekiqTestJob, given_args)
diff --git a/spec/lib/appsignal/rack/grape_middleware_spec.rb b/spec/lib/appsignal/rack/grape_middleware_spec.rb
index e6741198..0980ea65 100644
--- a/spec/lib/appsignal/rack/grape_middleware_spec.rb
+++ b/spec/lib/appsignal/rack/grape_middleware_spec.rb
@@ -19,12 +19,12 @@
     end
     let(:middleware) { Appsignal::Rack::GrapeMiddleware.new(api_endpoint) }
     let(:transaction) { http_request_transaction }
-    before { start_agent }
+    before do
+      stub_const("GrapeExample::Api", app)
+      start_agent
+    end
     around do |example|
-      GrapeExample = Module.new
-      GrapeExample.send(:const_set, :Api, app)
       keep_transactions { example.run }
-      Object.send(:remove_const, :GrapeExample)
     end
 
     def make_request(env)
diff --git a/spec/lib/appsignal_spec.rb b/spec/lib/appsignal_spec.rb
index 11de4496..c75713a7 100644
--- a/spec/lib/appsignal_spec.rb
+++ b/spec/lib/appsignal_spec.rb
@@ -520,10 +520,7 @@ def on_start
 
   describe ".load" do
     before do
-      TestLoader = define_loader(:appsignal_loader)
-    end
-    after do
-      Object.send(:remove_const, :TestLoader)
+      stub_const("TestLoader", define_loader(:appsignal_loader))
     end
 
     it "loads a loader" do
diff --git a/spec/lib/puma/appsignal_spec.rb b/spec/lib/puma/appsignal_spec.rb
index 46d45497..e7d5919e 100644
--- a/spec/lib/puma/appsignal_spec.rb
+++ b/spec/lib/puma/appsignal_spec.rb
@@ -100,7 +100,7 @@ def track_message(message)
   let(:expected_default_tags) { { "hostname" => hostname } }
   let(:stats_data) { { :backlog => 1 } }
   before do
-    module Puma
+    stub_const("Puma", Module.new do
       def self.stats
         JSON.dump(@_stats_data)
       end
@@ -112,30 +112,26 @@ def self.stats_hash
       def self._set_stats=(data)
         @_stats_data = data
       end
-
-      class Plugin
-        class << self
-          attr_reader :appsignal_plugin
-
-          def create(&block)
-            @appsignal_plugin = Class.new(::Puma::Plugin)
-            @appsignal_plugin.class_eval(&block)
-          end
+    end)
+    stub_const("Puma::Plugin", Class.new do
+      class << self
+        attr_reader :appsignal_plugin
+
+        def create(&block)
+          @appsignal_plugin = Class.new(::Puma::Plugin)
+          @appsignal_plugin.class_eval(&block)
         end
+      end
 
-        attr_reader :in_background_block
+      attr_reader :in_background_block
 
-        def in_background(&block)
-          @in_background_block = block
-        end
+      def in_background(&block)
+        @in_background_block = block
       end
-    end
+    end)
     load File.expand_path("../lib/puma/plugin/appsignal.rb", APPSIGNAL_SPEC_DIR)
   end
-  after do
-    Object.send(:remove_const, :Puma)
-    Object.send(:remove_const, :AppsignalPumaPlugin)
-  end
+  after { Object.send(:remove_const, :AppsignalPumaPlugin) }
 
   def run_plugin(stats_data, plugin, &block)
     Puma._set_stats = stats_data