diff --git a/test/test_mnn.py b/test/test_mnn.py
index 6d667ab..f1aa8c3 100644
--- a/test/test_mnn.py
+++ b/test/test_mnn.py
@@ -233,7 +233,7 @@ def test_single_sample_idx():
         )
         G = build_graph(data, sample_idx=np.repeat(1, len(data)))
     G2 = build_graph(data)
-    assert (G.K - G2.K).nnz == 0
+    np.testing.assert_array_equal(G.K, G2.K)
 
 
 def test_mnn_with_non_zero_indexed_sample_idx():