diff --git a/gptools-util/tests/test_fft.py b/gptools-util/tests/test_fft.py
index 6b5e987..5667ded 100644
--- a/gptools-util/tests/test_fft.py
+++ b/gptools-util/tests/test_fft.py
@@ -62,13 +62,16 @@ def test_transform_rfft_roundtrip(batch_shape: tuple[int], rfft_num: int, use_to
     np.testing.assert_allclose(z, x)
 
 
-def test_evaluate_log_prob_rfft2(batch_shape: tuple[int], rfft2_shape: int, use_torch: bool) \
-        -> None:
-    xs = coordgrid(*(np.linspace(0, 1, size, endpoint=False) for size in rfft2_shape))
-    kernel = kernels.ExpQuadKernel(np.random.gamma(10, 0.1), np.random.gamma(10, 0.01), 1) \
-        + kernels.DiagonalKernel(1e-2, 1)
+@pytest.mark.parametrize("kernel", [
+    kernels.ExpQuadKernel(np.random.gamma(10, 0.1), np.random.gamma(10, 0.01), 1.2),
+    kernels.MaternKernel(1.5, np.random.gamma(10, 0.1), np.random.gamma(10, 0.01), 1.3),
+    kernels.MaternKernel(2.5, np.random.gamma(10, 0.1), np.random.gamma(10, 0.01), 1.4),
+])
+def test_evaluate_log_prob_rfft2(kernel: kernels.Kernel, batch_shape: tuple[int], rfft2_shape: int,
+                                 use_torch: bool) -> None:
+    xs = coordgrid(*(np.linspace(0, kernel.period, size, endpoint=False) for size in rfft2_shape))
+    kernel = kernel + kernels.DiagonalKernel(1e-2, kernel.period)
     cov = kernel.evaluate(xs)
-    np.fill_diagonal(cov, np.diag(cov) + 1e-6)
     loc = np.random.normal(0, 1, xs.shape[0])
     dist = stats.multivariate_normal(loc, cov)
     y = dist.rvs(batch_shape)