diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 3c1726e..998106b 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,7 +12,7 @@ jobs:
     timeout-minutes: 5
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup ruby
         uses: ruby/setup-ruby@v1
@@ -28,21 +28,27 @@ jobs:
           bundle exec stree check Gemfile $(git ls-files '*.rb') $(git ls-files '*.rake') $(git ls-files '*.thor')
 
   test:
+    name: Ruby ${{ matrix.ruby }}, Sidekiq ${{ matrix.sidekiq }}, ${{ matrix.redis }}
     runs-on: ubuntu-latest
     timeout-minutes: 5
 
     services:
       redis:
-        image: redis
+        image: ${{ matrix.redis }}
         ports:
           - 6379:6379
 
     strategy:
       matrix:
-        ruby: ["3.1", "3.2", "3.3"]
+        ruby:    ["3.0", "3.1", "3.2", "3.3"]
+        redis:   ["redis", "valkey/valkey"]
+        sidekiq: ["6.5", "7.0", "7.1", "7.2", "7.3", "8.0", "8.1"]
+
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/sidekiq-${{ matrix.sidekiq }}.gemfile
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Setup ruby
         uses: ruby/setup-ruby@v1
@@ -59,7 +65,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Release Gem
         uses: discourse/publish-rubygems-action@v3
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2b2667e..69b31b1 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,3 +1,13 @@
+# 0.19.0 - 2025-12-04
+
+- Fix race condition in `MiniScheduler::Manager`
+
+# 0.18.0 - 2024-12-20
+
+- Add support for Sidekiq 7+
+- Remove support for Sidekiq < 6.5
+- Update minimum Ruby version to 3.0
+
 # 0.17.0 - 2024-08-06
 
 - Add `MiniScheduler::Manager.discover_running_scheduled_jobs` API to allow running scheduled jobs to easily be discovered on the
diff --git a/gemfiles/sidekiq-6.5.gemfile b/gemfiles/sidekiq-6.5.gemfile
new file mode 100644
index 0000000..74a077b
--- /dev/null
+++ b/gemfiles/sidekiq-6.5.gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "sidekiq", "~> 6.5.0"
diff --git a/gemfiles/sidekiq-7.0.gemfile b/gemfiles/sidekiq-7.0.gemfile
new file mode 100644
index 0000000..2e43d33
--- /dev/null
+++ b/gemfiles/sidekiq-7.0.gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "sidekiq", "~> 7.0.0"
diff --git a/gemfiles/sidekiq-7.1.gemfile b/gemfiles/sidekiq-7.1.gemfile
new file mode 100644
index 0000000..1bf9eca
--- /dev/null
+++ b/gemfiles/sidekiq-7.1.gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "sidekiq", "~> 7.1.0"
diff --git a/gemfiles/sidekiq-7.2.gemfile b/gemfiles/sidekiq-7.2.gemfile
new file mode 100644
index 0000000..a93c3fb
--- /dev/null
+++ b/gemfiles/sidekiq-7.2.gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "sidekiq", "~> 7.2.0"
diff --git a/gemfiles/sidekiq-7.3.gemfile b/gemfiles/sidekiq-7.3.gemfile
new file mode 100644
index 0000000..0e9dc69
--- /dev/null
+++ b/gemfiles/sidekiq-7.3.gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "sidekiq", "~> 7.3.0"
diff --git a/gemfiles/sidekiq-8.0.gemfile b/gemfiles/sidekiq-8.0.gemfile
new file mode 100644
index 0000000..3cc8105
--- /dev/null
+++ b/gemfiles/sidekiq-8.0.gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "sidekiq", "~> 8.0.0"
diff --git a/gemfiles/sidekiq-8.1.gemfile b/gemfiles/sidekiq-8.1.gemfile
new file mode 100644
index 0000000..6140cd1
--- /dev/null
+++ b/gemfiles/sidekiq-8.1.gemfile
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+source "https://rubygems.org"
+
+gemspec path: ".."
+
+gem "sidekiq", "~> 8.1.0"
diff --git a/lib/mini_scheduler.rb b/lib/mini_scheduler.rb
index fbf217b..962a6ca 100644
--- a/lib/mini_scheduler.rb
+++ b/lib/mini_scheduler.rb
@@ -5,6 +5,7 @@
 require "mini_scheduler/manager"
 require "mini_scheduler/distributed_mutex"
 require "sidekiq"
+require "redis"
 
 begin
   require "sidekiq/exception_handler"
@@ -16,26 +17,23 @@ def self.configure
     yield self
   end
 
-  class SidekiqExceptionHandler
-    if defined?(Sidekiq::ExceptionHandler)
-      extend Sidekiq::ExceptionHandler
-    else
-      def self.handle_exception(exception, context)
-        Sidekiq.handle_exception(exception, context)
-      end
+  SidekiqExceptionHandler =
+    if defined?(Sidekiq.default_configuration) # Sidekiq 7+
+      ->(ex, ctx, _config = nil) { Sidekiq.default_configuration.handle_exception(ex, ctx) }
+    else # Sidekiq 6.5
+      ->(ex, ctx, _config = nil) { Sidekiq.handle_exception(ex, ctx) }
     end
-  end
 
   def self.job_exception_handler(&blk)
     @job_exception_handler = blk if blk
     @job_exception_handler
   end
 
-  def self.handle_job_exception(ex, context = {})
+  def self.handle_job_exception(ex, context = {}, _config = nil)
     if job_exception_handler
       job_exception_handler.call(ex, context)
     else
-      SidekiqExceptionHandler.handle_exception(ex, context)
+      SidekiqExceptionHandler.call(ex, context)
     end
   end
 
diff --git a/lib/mini_scheduler/manager.rb b/lib/mini_scheduler/manager.rb
index 1b1cd4a..1295858 100644
--- a/lib/mini_scheduler/manager.rb
+++ b/lib/mini_scheduler/manager.rb
@@ -28,8 +28,8 @@ def initialize(manager)
         @keep_alive_thread =
           Thread.new do
             while !@stopped
-              @mutex.synchronize { keep_alive }
               sleep(@manager.keep_alive_duration / 2)
+              @mutex.synchronize { keep_alive }
             end
           end
 
@@ -348,7 +348,7 @@ def blocking_tick
     end
 
     def stop!
-      @runner.stop!
+      @runner&.stop!
       self.class.current.delete(@queue)
     end
 
@@ -357,7 +357,7 @@ def keep_alive_duration
     end
 
     def keep_alive(*ids)
-      ids = [identity_key, *@runner.worker_thread_ids] if ids.size == 0
+      ids = [identity_key, *@runner&.worker_thread_ids] if ids.size == 0
       ids.each { |identity_key| redis.setex identity_key, keep_alive_duration, "" }
     end
 
@@ -394,10 +394,10 @@ def self.hostname
         begin
           require "socket"
           Socket.gethostname
-        rescue => e
+        rescue StandardError
           begin
             `hostname`.strip
-          rescue => e
+          rescue StandardError
             "unknown_host"
           end
         end
diff --git a/lib/mini_scheduler/version.rb b/lib/mini_scheduler/version.rb
index bc91acd..216a946 100644
--- a/lib/mini_scheduler/version.rb
+++ b/lib/mini_scheduler/version.rb
@@ -1,5 +1,5 @@
 # frozen_string_literal: true
 
 module MiniScheduler
-  VERSION = "0.17.0"
+  VERSION = "0.18.0"
 end
diff --git a/lib/mini_scheduler/web.rb b/lib/mini_scheduler/web.rb
index 1634ffe..e40ef73 100644
--- a/lib/mini_scheduler/web.rb
+++ b/lib/mini_scheduler/web.rb
@@ -18,22 +18,24 @@ def self.find_schedules_by_time
       end
     end
 
-    def self.registered(app)
-      app.helpers do
-        def sane_time(time)
-          return unless time
-          time
-        end
+    module Helpers
+      def sane_time(time)
+        return unless time
+        time
+      end
 
-        def sane_duration(duration)
-          return unless duration
-          if duration < 1000
-            "#{duration}ms"
-          else
-            "#{"%.2f" % (duration / 1000.0)} secs"
-          end
+      def sane_duration(duration)
+        return unless duration
+        if duration < 1000
+          "#{duration}ms"
+        else
+          "#{"%.2f" % (duration / 1000.0)} secs"
         end
       end
+    end
+
+    def self.registered(app)
+      app.helpers Helpers
 
       app.get "/scheduler" do
         MiniScheduler.before_sidekiq_web_request&.call
@@ -72,5 +74,5 @@ def sane_duration(duration)
   end
 end
 
-Sidekiq::Web.register(MiniScheduler::Web)
+Sidekiq::Web.configure {|cfg| cfg.register(MiniScheduler::Web, name: nil, tab: nil, index: nil) }
 Sidekiq::Web.tabs["Scheduler"] = "scheduler"
diff --git a/mini_scheduler.gemspec b/mini_scheduler.gemspec
index 67e7423..fdc86a9 100644
--- a/mini_scheduler.gemspec
+++ b/mini_scheduler.gemspec
@@ -15,17 +15,17 @@ Gem::Specification.new do |spec|
   spec.homepage = "https://github.com/discourse/mini_scheduler"
   spec.license = "MIT"
 
-  spec.required_ruby_version = ">= 2.7.0"
+  spec.required_ruby_version = ">= 3.0.0"
 
   spec.files = `git ls-files`.split($/).reject { |s| s =~ /^(spec|\.)/ }
   spec.require_paths = ["lib"]
 
-  spec.add_runtime_dependency "sidekiq", ">= 4.2.3", "< 7.0"
+  spec.add_runtime_dependency "sidekiq", ">= 6.5", "< 9.0"
 
   spec.add_development_dependency "pg", "~> 1.0"
   spec.add_development_dependency "activesupport", "~> 7.0"
   spec.add_development_dependency "rspec", "~> 3.0"
-  spec.add_development_dependency "mocha", "~> 2.0"
+  spec.add_development_dependency "mocha", "~> 3.0"
   spec.add_development_dependency "guard", "~> 2.0"
   spec.add_development_dependency "guard-rspec", "~> 4.0"
   spec.add_development_dependency "redis", ">= 4.0"
diff --git a/spec/mini_scheduler/manager_spec.rb b/spec/mini_scheduler/manager_spec.rb
index 5491a99..606ee35 100644
--- a/spec/mini_scheduler/manager_spec.rb
+++ b/spec/mini_scheduler/manager_spec.rb
@@ -409,16 +409,19 @@ def queued_jobs(manager, with_hostname:)
 
     def expect_job_failure(ex, ctx)
       expect(ex).to be_kind_of ZeroDivisionError
-      expect(ctx).to match(
-        { message: "Error while running a scheduled job", job: { "class" => Testing::FailingJob } },
-      )
+      expect(ctx).to match a_hash_including(
+              message: "Error while running a scheduled job",
+              job: {
+                "class" => Testing::FailingJob,
+              },
+            )
     end
 
     context "with default handler" do
       class TempSidekiqLogger
         attr_accessor :exception, :context
 
-        def call(ex, ctx)
+        def call(ex, ctx, _config = nil)
           self.exception = ex
           self.context = ctx
         end
@@ -426,9 +429,17 @@ def call(ex, ctx)
 
       let(:logger) { TempSidekiqLogger.new }
 
-      before { Sidekiq.error_handlers << logger }
+      let(:error_handlers) do
+        if defined?(Sidekiq.default_configuration)
+          Sidekiq.default_configuration.error_handlers
+        else
+          Sidekiq.error_handlers
+        end
+      end
+
+      before { error_handlers << logger }
 
-      after { Sidekiq.error_handlers.delete(logger) }
+      after { error_handlers.delete(logger) }
 
       it "captures failed jobs" do
         manager.blocking_tick
@@ -438,7 +449,9 @@ def call(ex, ctx)
     end
 
     context "with custom handler" do
-      before { MiniScheduler.job_exception_handler { |ex, ctx| expect_job_failure(ex, ctx) } }
+      before do
+        MiniScheduler.job_exception_handler { |ex, ctx, _config = nil| expect_job_failure(ex, ctx) }
+      end
 
       after { MiniScheduler.instance_variable_set :@job_exception_handler, nil }
 
@@ -447,4 +460,11 @@ def call(ex, ctx)
       end
     end
   end
+
+  describe "#keep_alive" do
+    it "does not raise an error when `skip_runner` is true" do
+      manager = MiniScheduler::Manager.new(enable_stats: false, skip_runner: true)
+      expect { manager.keep_alive }.not_to raise_error
+    end
+  end
 end