diff --git a/src/backend/executor/nodeSetOp.c b/src/backend/executor/nodeSetOp.c
index bea30d6c8f0..5b7ff9c3748 100644
--- a/src/backend/executor/nodeSetOp.c
+++ b/src/backend/executor/nodeSetOp.c
@@ -104,7 +104,7 @@ build_hash_table(SetOpState *setopstate)
 												setopstate->hashfunctions,
 												node->cmpCollations,
 												node->numGroups,
-												0,
+												sizeof(SetOpStatePerGroupData),
 												setopstate->ps.state->es_query_cxt,
 												setopstate->tableContext,
 												econtext->ecxt_per_tuple_memory,