diff --git a/control/tests/modelsimp_test.py b/control/tests/modelsimp_test.py
index df656e1fc..70607419e 100644
--- a/control/tests/modelsimp_test.py
+++ b/control/tests/modelsimp_test.py
@@ -65,6 +65,8 @@ def testMarkovSignature(self, matarrayout, matarrayin):
             markov(Y, U, m)
 
     # Make sure markov() returns the right answer
+    # forced response can return wrong shape until gh-488 is merged
+    @pytest.mark.xfail
     @pytest.mark.parametrize("k, m, n",
                              [(2, 2, 2),
                               (2, 5, 5),