diff --git a/tests/client-dbus/tests/udev/test_predict.py b/tests/client-dbus/tests/udev/test_predict.py
index 7a6c131101..c3885ceaa2 100644
--- a/tests/client-dbus/tests/udev/test_predict.py
+++ b/tests/client-dbus/tests/udev/test_predict.py
@@ -219,8 +219,14 @@ def _check_prediction(self, prediction, mopool):
             prediction["total"],
         )
 
-        self.assertEqual(mopool.TotalPhysicalSize(), total_prediction)
-        self.assertEqual(total_physical_used, used_prediction)
+        self.assertEqual(
+            mopool.TotalPhysicalSize(),
+            total_prediction,
+            msg=f"Predicted sizes: {prediction}",
+        )
+        self.assertEqual(
+            total_physical_used, used_prediction, msg=f"Predicted sizes: {prediction}"
+        )
 
     def _test_prediction(self, pool_name, *, fs_specs=None, overprovision=True):
         """