diff --git a/src/llm/themes.py b/src/llm/themes.py
index 28946fd..881e466 100644
--- a/src/llm/themes.py
+++ b/src/llm/themes.py
@@ -140,7 +140,7 @@ def stamp(
             patches.append({"id": cid, "patch": json.dumps(patch)})
         if patches:
             with engine.begin() as conn:
-                conn.executemany(text(_UPDATE), patches)
+                conn.execute(text(_UPDATE), patches)  # a list of params = executemany
             stats["stamped"] += len(patches)
         log.info("themes: scanned=%d stamped=%d", stats["scanned"], stats["stamped"])
     return stats
diff --git a/tests/llm/test_themes.py b/tests/llm/test_themes.py
index bce602d..2503a75 100644
--- a/tests/llm/test_themes.py
+++ b/tests/llm/test_themes.py
@@ -34,13 +34,10 @@ def _engine(pages):
             r = MagicMock()
             r.fetchall.return_value = selects.pop(0)
             return r
+        updates.extend(params)  # an UPDATE with a list of params (executemany)
         return MagicMock()
 
-    def executemany(sql, params):
-        updates.extend(params)
-
     conn.execute.side_effect = execute
-    conn.executemany.side_effect = executemany
     return engine, updates