diff --git a/econml/iv/dml/_dml.py b/econml/iv/dml/_dml.py
index 835bbb522..0c0b90655 100644
--- a/econml/iv/dml/_dml.py
+++ b/econml/iv/dml/_dml.py
@@ -761,7 +761,7 @@ def predict(self, Y, T, X=None, W=None, Z=None, sample_weight=None, groups=None)
             TX_pred = np.tile(TX_pred.reshape(1, -1), (T.shape[0], 1))
         Y_res = Y - Y_pred.reshape(Y.shape)
         T_res = TXZ_pred.reshape(T.shape) - TX_pred.reshape(T.shape)
-        if T_res.sum() == 0:
+        if not T_res.any():
             raise ValueError(
                 """
                 All values of the treatment residual are 0,