diff --git a/tests/python_package_test/test_dask.py b/tests/python_package_test/test_dask.py
index 1ed7284ce305..c290c03d3de2 100644
--- a/tests/python_package_test/test_dask.py
+++ b/tests/python_package_test/test_dask.py
@@ -198,7 +198,7 @@ def _create_data(objective, n_samples=1_000, output='array', chunk_size=500, **k
 
 def _r2_score(dy_true, dy_pred):
     numerator = ((dy_true - dy_pred) ** 2).sum(axis=0, dtype=np.float64)
-    denominator = ((dy_true - dy_pred.mean(axis=0)) ** 2).sum(axis=0, dtype=np.float64)
+    denominator = ((dy_true - dy_true.mean(axis=0)) ** 2).sum(axis=0, dtype=np.float64)
     return (1 - numerator / denominator).compute()