diff --git a/kwant/tests/test_operator.py b/kwant/tests/test_operator.py
index a9545bf84e5030a1ac4aa082417ad83e5498b28b..cc76209e3b058243ddcb4f00929942737a91117c 100644
--- a/kwant/tests/test_operator.py
+++ b/kwant/tests/test_operator.py
@@ -77,7 +77,6 @@ def test_operator_construction():
             raises(ValueError, a, ket)
             raises(ValueError, a, ket, ket)
             raises(ValueError, a.act, ket)
-            raises(ValueError, a.act, ket, ket)
 
     # Test failure on non-hermitian
     for A in (ops.Density, ops.Current, ops.Source):