diff --git a/kwant/tests/test_kpm.py b/kwant/tests/test_kpm.py
index 7ae187339e51163549637cf44306643b7f816bf4..524cc57d78a97434ed6605f36b72d5833c5fd410 100644
--- a/kwant/tests/test_kpm.py
+++ b/kwant/tests/test_kpm.py
@@ -80,6 +80,13 @@ def test_conductivity():
         cond = kwant.kpm.conductivity(syst, alpha=alpha, beta=beta,
                                         positions=None, **kpm_params)
 
+    # test when 'norbs' not provided
+    n = lat.norbs
+    lat.norbs = None
+    cond = kwant.kpm.conductivity(syst, alpha=alpha, beta=beta,
+                                  positions=None, **kpm_params)
+    lat.norbs = n
+
     # test system or hamiltonian, no positions, but velocity operators
     cond_xx = kwant.kpm.conductivity(syst, alpha='x', beta='x',
                                      positions=None, **kpm_params)