diff --git a/src/backend/optimizer/plan/planner.c b/src/backend/optimizer/plan/planner.c
index ecdd7280eb..d58635c887 100644
--- a/src/backend/optimizer/plan/planner.c
+++ b/src/backend/optimizer/plan/planner.c
@@ -776,6 +776,27 @@ subquery_planner(PlannerGlobal *glob, Query *parse,
 		}
 	}
 
+	/*
+	 * Now that we are done preprocessing expressions, and in particular done
+	 * flattening join alias variables, get rid of the joinaliasvars lists.
+	 * They no longer match what expressions in the rest of the tree look
+	 * like, because we have not preprocessed expressions in those lists (and
+	 * do not want to; for example, expanding a SubLink there would result in
+	 * a useless unreferenced subplan).  Leaving them in place simply creates
+	 * a hazard for later scans of the tree.  We could try to prevent that by
+	 * using QTW_IGNORE_JOINALIASES in every tree scan done after this point,
+	 * but that doesn't sound very reliable.
+	 */
+	if (root->hasJoinRTEs)
+	{
+		foreach(l, parse->rtable)
+		{
+			RangeTblEntry *rte = lfirst_node(RangeTblEntry, l);
+
+			rte->joinaliasvars = NIL;
+		}
+	}
+
 	/*
 	 * In some cases we may want to transfer a HAVING clause into WHERE. We
 	 * cannot do so if the HAVING clause contains aggregates (obviously) or
@@ -902,11 +923,12 @@ preprocess_expression(PlannerInfo *root, Node *expr, int kind)
 
 	/*
 	 * If the query has any join RTEs, replace join alias variables with
-	 * base-relation variables.  We must do this before sublink processing,
-	 * else sublinks expanded out from join aliases would not get processed.
-	 * We can skip it in non-lateral RTE functions, VALUES lists, and
-	 * TABLESAMPLE clauses, however, since they can't contain any Vars of the
-	 * current query level.
+	 * base-relation variables.  We must do this first, since any expressions
+	 * we may extract from the joinaliasvars lists have not been preprocessed.
+	 * For example, if we did this after sublink processing, sublinks expanded
+	 * out from join aliases would not get processed.  But we can skip this in
+	 * non-lateral RTE functions, VALUES lists, and TABLESAMPLE clauses, since
+	 * they can't contain any Vars of the current query level.
 	 */
 	if (root->hasJoinRTEs &&
 		!(kind == EXPRKIND_RTFUNC ||
diff --git a/src/test/regress/expected/subselect.out b/src/test/regress/expected/subselect.out
index f3ebad5857..992d29bb86 100644
--- a/src/test/regress/expected/subselect.out
+++ b/src/test/regress/expected/subselect.out
@@ -678,6 +678,20 @@ with q as (select max(f1) from int4_tbl group by f1 order by f1)
  (2147483647)
 (5 rows)
 
+--
+-- Test case for sublinks pulled up into joinaliasvars lists in an
+-- inherited update/delete query
+--
+begin;  --  this shouldn't delete anything, but be safe
+delete from road
+where exists (
+  select 1
+  from
+    int4_tbl cross join
+    ( select f1, array(select q1 from int8_tbl) as arr
+      from text_tbl ) ss
+  where road.name = ss.f1 );
+rollback;
 --
 -- Test case for sublinks pushed down into subselects via join alias expansion
 --
diff --git a/src/test/regress/sql/subselect.sql b/src/test/regress/sql/subselect.sql
index 5ac8badabe..0d2dd2f1d8 100644
--- a/src/test/regress/sql/subselect.sql
+++ b/src/test/regress/sql/subselect.sql
@@ -376,6 +376,24 @@ select q from (select max(f1) from int4_tbl group by f1 order by f1) q;
 with q as (select max(f1) from int4_tbl group by f1 order by f1)
   select q from q;
 
+--
+-- Test case for sublinks pulled up into joinaliasvars lists in an
+-- inherited update/delete query
+--
+
+begin;  --  this shouldn't delete anything, but be safe
+
+delete from road
+where exists (
+  select 1
+  from
+    int4_tbl cross join
+    ( select f1, array(select q1 from int8_tbl) as arr
+      from text_tbl ) ss
+  where road.name = ss.f1 );
+
+rollback;
+
 --
 -- Test case for sublinks pushed down into subselects via join alias expansion
 --