diff --git a/hugr-py/tests/test_hugr_build.py b/hugr-py/tests/test_hugr_build.py
index 5d54cb177..89e549108 100644
--- a/hugr-py/tests/test_hugr_build.py
+++ b/hugr-py/tests/test_hugr_build.py
@@ -307,7 +307,7 @@ def test_ancestral_sibling():
     "val",
     [
         val.Function(simple_id().hugr),
-        val.Sum(1, tys.Sum([[INT_T], [tys.Bool, INT_T]]), [IntVal(34)]),
+        val.Sum(1, tys.Sum([[INT_T], [tys.Bool, INT_T]]), [val.TRUE, IntVal(34)]),
         val.Tuple([val.TRUE, IntVal(23)]),
     ],
 )