diff --git a/lib/active_job/job_proxy.rb b/lib/active_job/job_proxy.rb
index 8a586242..630b62d3 100644
--- a/lib/active_job/job_proxy.rb
+++ b/lib/active_job/job_proxy.rb
@@ -27,7 +27,7 @@ def perform_now
   end
 
   def duration
-    finished_at - scheduled_at
+    finished_at - (scheduled_at || enqueued_at)
   end
 
   ActiveJob::JobsRelation::STATUSES.each do |status|
diff --git a/test/active_job/job_proxy_test.rb b/test/active_job/job_proxy_test.rb
index c8c2446d..2e2ccc14 100644
--- a/test/active_job/job_proxy_test.rb
+++ b/test/active_job/job_proxy_test.rb
@@ -6,4 +6,13 @@ class ActiveJob::JobProxyTest < ActiveSupport::TestCase
     job_proxy = ActiveJob::JobProxy.new(job.serialize)
     assert_instance_of DummyJob, ActiveJob::Base.deserialize(job_proxy.serialize)
   end
+
+  test "#duration does not break if scheduled_at is not set" do
+    job = DummyJob.new(123)
+    job_proxy = ActiveJob::JobProxy.new(job.serialize)
+    job_proxy.finished_at = job_proxy.enqueued_at + 5.seconds
+
+    assert_nil job_proxy.scheduled_at
+    assert_equal 5.seconds, job_proxy.duration
+  end
 end