diff --git a/src/backend/optimizer/plan/setrefs.c b/src/backend/optimizer/plan/setrefs.c
index 4348bfef60..186fc8014b 100644
--- a/src/backend/optimizer/plan/setrefs.c
+++ b/src/backend/optimizer/plan/setrefs.c
@@ -2205,7 +2205,7 @@ fix_scan_expr_mutator(Node *node, fix_scan_expr_context *context)
 		/* At scan level, we should always just evaluate the contained expr */
 		PlaceHolderVar *phv = (PlaceHolderVar *) node;
 
-		Assert(phv->phnullingrels == NULL);
+		/* XXX can we assert something about phnullingrels? */
 		return fix_scan_expr_mutator((Node *) phv->phexpr, context);
 	}
 	if (IsA(node, AlternativeSubPlan))
diff --git a/src/test/regress/expected/join.out b/src/test/regress/expected/join.out
index 87e1276804..e73ba93ca3 100644
--- a/src/test/regress/expected/join.out
+++ b/src/test/regress/expected/join.out
@@ -3599,6 +3599,20 @@ where f1 in ( select c3.f1 from ctetable c2 full join ctetable c3 on true );
   1
 (1 row)
 
+-- Test PHV that winds up in a Result node, despite having nonempty nullingrels
+explain (verbose, costs off)
+select table_catalog, table_name
+from int4_tbl t1
+  inner join (int8_tbl t2
+              left join information_schema.column_udt_usage on null)
+  on null;
+                                                    QUERY PLAN                                                     
+-------------------------------------------------------------------------------------------------------------------
+ Result
+   Output: (current_database())::information_schema.sql_identifier, (c.relname)::information_schema.sql_identifier
+   One-Time Filter: false
+(3 rows)
+
 --
 -- test inlining of immutable functions
 --
diff --git a/src/test/regress/sql/join.sql b/src/test/regress/sql/join.sql
index 2bb24dbfcd..ed26ffd8a8 100644
--- a/src/test/regress/sql/join.sql
+++ b/src/test/regress/sql/join.sql
@@ -1181,6 +1181,14 @@ with ctetable as not materialized ( select 1 as f1 )
 select * from ctetable c1
 where f1 in ( select c3.f1 from ctetable c2 full join ctetable c3 on true );
 
+-- Test PHV that winds up in a Result node, despite having nonempty nullingrels
+explain (verbose, costs off)
+select table_catalog, table_name
+from int4_tbl t1
+  inner join (int8_tbl t2
+              left join information_schema.column_udt_usage on null)
+  on null;
+
 --
 -- test inlining of immutable functions
 --