diff --git a/cmd/ztest.c b/cmd/ztest.c
index 398c519cf..59c4be225 100644
--- a/cmd/ztest.c
+++ b/cmd/ztest.c
@@ -3767,7 +3767,7 @@ ztest_vdev_attach_detach(ztest_ds_t *zd, uint64_t id)
 	else if (ashift > oldvd->vdev_top->vdev_ashift)
 		expected_error = EDOM;
 	else if (newvd_is_dspare && pvd != vdev_draid_spare_get_parent(newvd))
-		expected_error = ENOTSUP;
+		expected_error = EINVAL;
 	else
 		expected_error = 0;