diff --git a/tooling/economy-db/import_economics.py b/tooling/economy-db/import_economics.py
index be7c80887..3c055fb19 100755
--- a/tooling/economy-db/import_economics.py
+++ b/tooling/economy-db/import_economics.py
@@ -1374,7 +1374,9 @@ def populate_atlas_city_names_corps(conn: sqlite3.Connection, dry_run: bool) ->
         # Try to find a matching atlas_city_names row in the same system
         body_ids_in_sys = sys_body_ids.get(headquarters_system, set())
         match_id: int | None = None
-        for body_id in body_ids_in_sys:
+        # sorted() for determinism: on a name collision across bodies in the
+        # same system, set iteration order is not stable (D-010 #4).
+        for body_id in sorted(body_ids_in_sys):
             key = (body_id, city_name.lower())
             if key in existing:
                 match_id = existing[key]