diff --git a/flamenco_worker/upstream_update_queue.py b/flamenco_worker/upstream_update_queue.py
index cda9e61effaa0e7352781700eb953b930432192d..65cca0bf69bd3d2320b13265de84ed532446e7ef 100644
--- a/flamenco_worker/upstream_update_queue.py
+++ b/flamenco_worker/upstream_update_queue.py
@@ -139,7 +139,7 @@ class TaskUpdateQueue:
                     # The task was assigned to another worker, so we're not allowed to
                     # push updates for it. We have to un-queue this update, as it will
                     # never be accepted.
-                    self._log.warning('Task was assigned to another worker, discarding update.')
+                    self._log.warning('discarding update, Manager says %s', resp.text)
                 else:
                     resp.raise_for_status()
                     self._log.debug('Master accepted pushed update.')
diff --git a/tests/mock_responses.py b/tests/mock_responses.py
index 9d2d534e37e6e2220a5ca14c0723300899f452e6..e8bb6b2e1bb1829e34633b2fe5e8ce0617d58263 100644
--- a/tests/mock_responses.py
+++ b/tests/mock_responses.py
@@ -23,6 +23,24 @@ class JsonResponse:
         raise requests.HTTPError(self.status_code)
 
 
+@attr.s
+class TextResponse:
+    """Mocked HTTP response returning text.
+
+    Maybe we want to switch to using unittest.mock.Mock for this,
+    or to using the responses package.
+    """
+
+    text = attr.ib(default='', validator=attr.validators.instance_of(str))
+    status_code = attr.ib(default=200, validator=attr.validators.instance_of(int))
+
+    def raise_for_status(self):
+        if 200 <= self.status_code < 300:
+            return
+
+        raise requests.HTTPError(self.status_code)
+
+
 @attr.s
 class EmptyResponse:
     """Mocked HTTP response returning an empty 204.
diff --git a/tests/test_upstream_update_queue.py b/tests/test_upstream_update_queue.py
index 4f8083a68bd16f7a1212ef89a002da246df4767a..85a4d65b45450e3c5e23f72bae496ed2460d9aa2 100644
--- a/tests/test_upstream_update_queue.py
+++ b/tests/test_upstream_update_queue.py
@@ -152,7 +152,7 @@ class TaskUpdateQueueTest(AbstractWorkerTest):
         """A 409 Conflict response should discard a queued task update.
         """
 
-        from mock_responses import JsonResponse, EmptyResponse
+        from mock_responses import TextResponse
 
         # Try different value types
         payload = {'key': 'value',
@@ -165,7 +165,7 @@ class TaskUpdateQueueTest(AbstractWorkerTest):
             nonlocal tries
             tries += 1
             self.shutdown_future.cancel()
-            return JsonResponse({}, status_code=409)
+            return TextResponse("no", status_code=409)
 
         self.manager.post.side_effect = push_callback