diff --git a/priv/python/albedo_plugins/cua.py b/priv/python/albedo_plugins/cua.py
index 6da4e9fc..34447f05 100644
--- a/priv/python/albedo_plugins/cua.py
+++ b/priv/python/albedo_plugins/cua.py
@@ -979,8 +979,7 @@ class _DriverClient:
                         await asyncio.wait_for(process.wait(), timeout=1.0)
         if stderr_task is not None:
             stderr_task.cancel()
-            with contextlib.suppress(Exception):
-                await stderr_task
+            await asyncio.wait({stderr_task})
 
     async def close(self) -> None:
         async with self._lock:
diff --git a/test/e2e/cua_test.py b/test/e2e/cua_test.py
index e7688c4d..e84e88b4 100644
--- a/test/e2e/cua_test.py
+++ b/test/e2e/cua_test.py
@@ -380,7 +380,12 @@ Path({str(marker)!r}).write_text("ok", encoding="utf-8")
             app.prompt(session, "drive calculator").close()
             app.idle(session)
 
-            self.assertTrue(marker.exists(), app.stream_page(session))
+            if not marker.exists():
+                history = app.history(session)["items"]
+                raise AssertionError(
+                    "CUA cell did not write its completion marker: "
+                    + json.dumps(history[-2:], default=str)
+                )
             sent = json.dumps(provider.requests[-1]["request"])
             encoded = re.findall(r"data:image/png;base64,([A-Za-z0-9+/=]+)", sent)
             self.assertEqual(len(encoded), 2)