diff --git a/src/backend/utils/adt/datum.c b/src/backend/utils/adt/datum.c
index f02a5e7..eca46e8 100644
--- a/src/backend/utils/adt/datum.c
+++ b/src/backend/utils/adt/datum.c
@@ -338,8 +338,19 @@ datumSerialize(Datum value, bool isnull, bool typByVal, int typLen,
 		}
 		else if (eoh)
 		{
-			EOH_flatten_into(eoh, (void *) *start_address, header);
+			char	   *res;
+
+			/*
+			 * EOH_flatten_into expects the target address to be maxaligned so
+			 * can't directly pass start_address.
+			 */
+			res = (char *) palloc(header);
+			EOH_flatten_into(eoh, (void *) res, header);
+			memcpy(*start_address, res, header);
 			*start_address += header;
+
+			/* be tidy. */
+			pfree(res);
 		}
 		else
 		{
diff --git a/src/test/regress/expected/select_parallel.out b/src/test/regress/expected/select_parallel.out
index 26409d3..e05379d 100644
--- a/src/test/regress/expected/select_parallel.out
+++ b/src/test/regress/expected/select_parallel.out
@@ -1088,6 +1088,38 @@ ORDER BY 1, 2, 3;
 ------------------------------+---------------------------+-------------+--------------
 (0 rows)
 
+--test expanded value representation
+SAVEPOINT settings;
+CREATE DOMAIN arrdomain AS int[];
+CREATE FUNCTION make_psafe_ad(int,int) returns arrdomain as
+  'declare x arrdomain;
+   begin
+     x := array[$1,$2];
+     return x;
+   end' language plpgsql parallel safe;
+CREATE TABLE tarrdomain(c1 int, c2 arrdomain);
+INSERT INTO tarrdomain values(1, array[1,2]);
+ANALYZE tarrdomain;
+SET force_parallel_mode=1;
+PREPARE stmt_sel_domain(arrdomain) AS SELECT * FROM tarrdomain where c2 = $1;
+EXPLAIN (COSTS OFF) EXECUTE stmt_sel_domain(make_psafe_ad(1,2));
+                       QUERY PLAN                       
+--------------------------------------------------------
+ Gather
+   Workers Planned: 1
+   Single Copy: true
+   ->  Seq Scan on tarrdomain
+         Filter: ((c2)::integer[] = '{1,2}'::integer[])
+(5 rows)
+
+EXECUTE stmt_sel_domain(make_psafe_ad(1,2));
+ c1 |  c2   
+----+-------
+  1 | {1,2}
+(1 row)
+
+DEALLOCATE stmt_sel_domain;
+ROLLBACK TO SAVEPOINT settings;
 -- test interation between subquery and partial_paths
 SET LOCAL min_parallel_table_scan_size TO 0;
 CREATE VIEW tenk1_vw_sec WITH (security_barrier) AS SELECT * FROM tenk1;
diff --git a/src/test/regress/sql/select_parallel.sql b/src/test/regress/sql/select_parallel.sql
index 938c708..d72e131 100644
--- a/src/test/regress/sql/select_parallel.sql
+++ b/src/test/regress/sql/select_parallel.sql
@@ -410,6 +410,27 @@ ORDER BY 1;
 SELECT * FROM information_schema.foreign_data_wrapper_options
 ORDER BY 1, 2, 3;
 
+--test expanded value representation
+SAVEPOINT settings;
+CREATE DOMAIN arrdomain AS int[];
+
+CREATE FUNCTION make_psafe_ad(int,int) returns arrdomain as
+  'declare x arrdomain;
+   begin
+     x := array[$1,$2];
+     return x;
+   end' language plpgsql parallel safe;
+
+CREATE TABLE tarrdomain(c1 int, c2 arrdomain);
+INSERT INTO tarrdomain values(1, array[1,2]);
+ANALYZE tarrdomain;
+SET force_parallel_mode=1;
+PREPARE stmt_sel_domain(arrdomain) AS SELECT * FROM tarrdomain where c2 = $1;
+EXPLAIN (COSTS OFF) EXECUTE stmt_sel_domain(make_psafe_ad(1,2));
+EXECUTE stmt_sel_domain(make_psafe_ad(1,2));
+DEALLOCATE stmt_sel_domain;
+ROLLBACK TO SAVEPOINT settings;
+
 -- test interation between subquery and partial_paths
 SET LOCAL min_parallel_table_scan_size TO 0;
 CREATE VIEW tenk1_vw_sec WITH (security_barrier) AS SELECT * FROM tenk1;