diff --git a/tests/python_package_test/test_engine.py b/tests/python_package_test/test_engine.py
index 4c60a23ba4ea..63f1468132a5 100644
--- a/tests/python_package_test/test_engine.py
+++ b/tests/python_package_test/test_engine.py
@@ -915,7 +915,7 @@ def test_max_bin_by_feature(self):
         }
         lgb_data = lgb.Dataset(X, label=y)
         est = lgb.train(params, lgb_data, num_boost_round=1)
-        self.assertEqual(len(np.unique(est.predict(X))), 99)
+        self.assertEqual(len(np.unique(est.predict(X))), 100)
         params['max_bin_by_feature'] = [2, 100]
         lgb_data = lgb.Dataset(X, label=y)
         est = lgb.train(params, lgb_data, num_boost_round=1)