diff --git a/lenskit/lenskit/splitting/users.py b/lenskit/lenskit/splitting/users.py
index d48a3afe4..da9feb975 100644
--- a/lenskit/lenskit/splitting/users.py
+++ b/lenskit/lenskit/splitting/users.py
@@ -162,7 +162,9 @@ def _make_split(
     test = {}
 
     for u in test_us:
-        row = data.user_row(u)
+        profile = data.user_row(u)
+        assert profile is not None
+        row = profile.item_list()
         assert row is not None
         u_test = method(row)
         test[u] = u_test