diff --git a/grudge/models/wave.py b/grudge/models/wave.py
index b22ff159..9f07797d 100644
--- a/grudge/models/wave.py
+++ b/grudge/models/wave.py
@@ -191,7 +191,7 @@ def estimate_rk4_timestep(self, actx, dcoll, **kwargs):
         volm_discr = dcoll.discr_from_dd(DD_VOLUME_ALL)
         tpe = any(not isinstance(grp, SimplexElementGroupBase)
                   for grp in volm_discr.groups)
-        fudge_factor = 0.23 if tpe else 0.38
+        fudge_factor = 0.233 if tpe else 0.38
         return fudge_factor * super().estimate_rk4_timestep(
             actx,  dcoll, **kwargs)
 
diff --git a/test/test_dt_utils.py b/test/test_dt_utils.py
index aa6ebc09..04375a37 100644
--- a/test/test_dt_utils.py
+++ b/test/test_dt_utils.py
@@ -47,6 +47,7 @@
 
 logger = logging.getLogger(__name__)
 from meshmode import _acf  # noqa: F401
+from meshmode.mesh.io import read_gmsh
 
 
 @pytest.mark.parametrize("name", ["interval", "box2d", "box3d"])
@@ -156,35 +157,46 @@ def rhs(x):
     assert np.allclose(np.diag(mat), 3*2*2 + 2)
 
 
-@pytest.mark.parametrize("dim", [1, 2])
+#                          ("simple_tets.msh", 3, False, False),
+#                          ("simple_hexs.msh", 3, True, False)])
 @pytest.mark.parametrize("degree", [2, 4])
-@pytest.mark.parametrize("tpe", [False, True])
-def test_wave_dt_estimate(actx_factory, dim, degree, tpe, visualize=False):
+@pytest.mark.parametrize(("meshfile", "dim", "tpe", "warp"),
+                         [(None, 1, False, False),
+                          (None, 2, False, False),
+                          (None, 2, False, True),
+                          (None, 2, True, False),
+                          (None, 2, True, True),])
+def test_wave_dt_estimate(actx_factory, degree, meshfile, dim, tpe, warp,
+                          visualize=False):
     actx = actx_factory()
 
     # {{{ cases
-    if dim == 1 and tpe:
-        pytest.skip("Skipping 1D test for tensor product elements.")
-
     from meshmode.mesh import TensorProductElementGroup
     group_cls = TensorProductElementGroup if tpe else None
     import meshmode.mesh.generation as mgen
 
-    a = [0, 0, 0]
-    b = [1, 1, 1]
-    mesh = mgen.generate_regular_rect_mesh(
-            a=a[:dim], b=b[:dim],
-            nelements_per_axis=(3,)*dim,
-            group_cls=group_cls)
-
-    assert mesh.dim == dim
-
+    if meshfile is None:
+        if warp:
+            mesh = mgen.generate_warped_rect_mesh(
+                dim=dim, order=2, nelements_side=3, group_cls=group_cls)
+        else:
+            a = [0, 0, 0]
+            b = [1, 1, 1]
+            mesh = mgen.generate_regular_rect_mesh(
+                a=a[:dim], b=b[:dim],
+                nelements_per_axis=(3,)*dim,
+                group_cls=group_cls)
+        assert mesh.dim == dim
+    else:
+        mesh_construction_kwargs = {"force_positive_orientation": True}
+        mesh = read_gmsh(meshfile,
+                         mesh_construction_kwargs=mesh_construction_kwargs)
     dcoll = make_discretization_collection(actx, mesh, order=degree)
 
     from grudge.models.wave import WeakWaveOperator
     wave_op = WeakWaveOperator(dcoll, c=1)
     rhs = actx.compile(
-            lambda w: wave_op.operator(t=0, w=w))
+        lambda w: wave_op.operator(t=0, w=w))
 
     from pytools.obj_array import make_obj_array
     fields = make_obj_array([dcoll.zeros(actx) for i in range(dim+1)])
@@ -212,7 +224,8 @@ def test_wave_dt_estimate(actx_factory, dim, degree, tpe, visualize=False):
         import matplotlib.pyplot as plt
         plt.contour(re, im, sf_grid, [0.25, 0.5, 0.75, 0.9, 1, 1.1])
         plt.colorbar()
-        plt.plot(dt_est * eigvals.real, dt_est * eigvals.imag, "x")
+        plt.plot(dt_est * eigvals.real, dt_est * eigvals.imag,
+                 "x")
         plt.grid()
         plt.show()
 
@@ -230,7 +243,7 @@ def test_wave_dt_estimate(actx_factory, dim, degree, tpe, visualize=False):
         print(f"Stable timestep is {max(stable_dt_factors):.2f}x the estimate")
     else:
         print("Stable timestep estimate appears to be sharp")
-    assert not stable_dt_factors or max(stable_dt_factors) < 1.5, stable_dt_factors
+    assert not stable_dt_factors or max(stable_dt_factors) < 1.54, stable_dt_factors
 
 
 # You can test individual routines by typing