diff --git a/example-app/README.md b/example-app/README.md
index a365c5a..587397c 100644
--- a/example-app/README.md
+++ b/example-app/README.md
@@ -7,3 +7,12 @@ To run:
 bundle
 bundle exec clock
 ```
+
+To test invocation of existing signal handlers, put this code at the very top of exe/clock:
+
+```ruby
+Signal.trap('INT') do
+  puts "This is a well-behaving INT handler from outside of ruby-clock"
+  exit
+end
+```
diff --git a/exe/clock b/exe/clock
index 6ca230f..7e55fc5 100755
--- a/exe/clock
+++ b/exe/clock
@@ -4,6 +4,7 @@ require 'ruby-clock'
 require "ruby-clock/dsl"
 RubyClock.detect_and_load_rails_app
 require 'rufus_monkeypatch'
+RubyClock.instance.listen_for_shutdown
 RubyClock.instance.listen_to_signals
 RubyClock.instance.prepare_rake
 RubyClock.instance.schedule.pause
diff --git a/lib/ruby-clock.rb b/lib/ruby-clock.rb
index d7ea7b1..43af89d 100644
--- a/lib/ruby-clock.rb
+++ b/lib/ruby-clock.rb
@@ -15,6 +15,7 @@ class RubyClock
   include RubyClock::AroundActions
 
   attr_accessor :on_error, :around_trigger_code_location
+  attr_accessor :should_shutdown, :old_shutdown_handler
 
   def initialize
     set_up_around_actions
@@ -24,6 +25,22 @@ def wait_seconds
     ENV['RUBY_CLOCK_SHUTDOWN_WAIT_SECONDS']&.to_i || 29
   end
 
+  def listen_for_shutdown
+    Thread.new do
+      loop do
+        sleep 1
+        if should_shutdown
+          shutdown
+          if old_shutdown_handler
+            old_shutdown_handler.call
+          else
+            exit
+          end
+        end
+      end
+    end
+  end
+
   def shutdown
     puts "Shutting down ruby-clock. Waiting #{wait_seconds} seconds for jobs to finish..."
     schedule.shutdown(wait: wait_seconds)
@@ -34,12 +51,10 @@ def listen_to_signals
     signals = %w[INT TERM]
     signals.each do |signal|
       old_handler = Signal.trap(signal) do
-        shutdown
         if old_handler.respond_to?(:call)
-          old_handler.call
-        else
-          exit
+          self.old_shutdown_handler = old_handler
         end
+        self.should_shutdown = true
       end
     end
     puts "RUBY_CLOCK_SHUTDOWN_WAIT_SECONDS is set to #{wait_seconds}"