diff --git a/lib/good_job.rb b/lib/good_job.rb
index c0389f7e8..1521f26bd 100644
--- a/lib/good_job.rb
+++ b/lib/good_job.rb
@@ -126,13 +126,13 @@ def self.restart(timeout: -1)
     _shutdown_all(_executables, :restart, timeout: timeout)
   end
 
-  # Sends +#shutdown+ or +#restart+ to executable objects ({GoodJob::Notifier}, {GoodJob::Poller}, {GoodJob::Scheduler})
-  # @param executables [Array<Notifier, Poller, Scheduler, MultiScheduler>] Objects to shut down.
+  # Sends +#shutdown+ or +#restart+ to executable objects ({GoodJob::Notifier}, {GoodJob::Poller}, {GoodJob::Scheduler}, {GoodJob::MultiScheduler}, {GoodJob::CronManager})
+  # @param executables [Array<Notifier, Poller, Scheduler, MultiScheduler, CronManager>] Objects to shut down.
   # @param method_name [:symbol] Method to call, e.g. +:shutdown+ or +:restart+.
   # @param timeout [nil,Numeric]
   # @return [void]
   def self._shutdown_all(executables, method_name = :shutdown, timeout: -1)
-    if timeout.positive?
+    if timeout.is_a?(Numeric) && timeout.positive?
       executables.each { |executable| executable.send(method_name, timeout: nil) }
 
       stop_at = Time.current + timeout
diff --git a/spec/lib/good_job_spec.rb b/spec/lib/good_job_spec.rb
index d331e367a..02a8e1c66 100644
--- a/spec/lib/good_job_spec.rb
+++ b/spec/lib/good_job_spec.rb
@@ -2,8 +2,9 @@
 require 'rails_helper'
 
 describe GoodJob do
-  let(:configuration) { GoodJob::Configuration.new({ queues: 'mice:1', poll_interval: -1 }) }
-  let!(:scheduler) { GoodJob::Scheduler.from_configuration(configuration) }
+  let(:configuration) { GoodJob::Configuration.new({ queues: 'mice:1;elephants:1', poll_interval: -1 }) }
+  let!(:multi_scheduler) { GoodJob::Scheduler.from_configuration(configuration) }
+  let(:scheduler) { multi_scheduler.schedulers.first }
   let!(:notifier) { GoodJob::Notifier.new([scheduler, :create_thread]) }
 
   describe '.shutdown' do
@@ -13,6 +14,13 @@
       expect(scheduler.shutdown?).to eq true
       expect(notifier.shutdown?).to eq true
     end
+
+    it 'shuts down when there is a timeout set' do
+      described_class.shutdown(timeout: 5)
+
+      expect(scheduler.shutdown?).to eq true
+      expect(notifier.shutdown?).to eq true
+    end
   end
 
   describe '.shutdown?' do
@@ -33,6 +41,14 @@
     end
   end
 
+  describe '._shutdown_all' do
+    it 'delegates shutdown methods to multiple instances' do
+      expect do
+        described_class._shutdown_all([multi_scheduler, notifier], timeout: 5)
+      end.to change(described_class, :shutdown?).from(false).to(true)
+    end
+  end
+
   describe '.reperform_jobs_on_standard_error' do
     around do |example|
       original_retry_on_unhandled_error = described_class.retry_on_unhandled_error