diff --git a/test/py/ganeti.objects_unittest.py b/test/py/ganeti.objects_unittest.py
index 719a4a12aab3a3ddde59d35a3627486f799d92ff..e111e33bcb422f0b73a342dea6ddba2eabdb7f0d 100755
--- a/test/py/ganeti.objects_unittest.py
+++ b/test/py/ganeti.objects_unittest.py
@@ -678,6 +678,14 @@ class TestInstancePolicy(unittest.TestCase):
       self._AssertIPolicyIsFull(policy)
       self._AssertIPolicyMerged(constants.IPOLICY_DEFAULTS, diff_pol, policy)
 
+  def testFillIPolicyKeepsUnknown(self):
+    INVALID_KEY = "invalid_ipolicy_key"
+    diff_pol = {
+      INVALID_KEY: None,
+      }
+    policy = objects.FillIPolicy(constants.IPOLICY_DEFAULTS, diff_pol)
+    self.assertTrue(INVALID_KEY in policy)
+
 
 if __name__ == "__main__":
   testutils.GanetiTestProgram()