diff --git a/tests/test_recon/test_algorithm.py b/tests/test_recon/test_algorithm.py
index 4bb16fae..a650fe1c 100644
--- a/tests/test_recon/test_algorithm.py
+++ b/tests/test_recon/test_algorithm.py
@@ -64,6 +64,7 @@ def test_reconstruct_FBP_3(data, flats, darks, ensure_clean_memory):
     assert_allclose(
         np.mean(recon_data, axis=(0, 2)).sum(), -0.03229, rtol=1e-06, atol=1e-5
     )
+    assert isinstance(recon_data, np.ndarray)
     assert recon_data.dtype == np.float32
     assert recon_data.shape == (210, 128, 210)