diff --git a/contrib/postgres_fdw/postgres_fdw.c b/contrib/postgres_fdw/postgres_fdw.c
index 465f43cd7c..d79e4ccbe3 100644
--- a/contrib/postgres_fdw/postgres_fdw.c
+++ b/contrib/postgres_fdw/postgres_fdw.c
@@ -3488,30 +3488,30 @@ foreign_join_ok(PlannerInfo *root, RelOptInfo *joinrel, JoinType jointype,
 	{
 		case JOIN_INNER:
 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
-											   fpinfo_i->remote_conds);
+										  list_copy(fpinfo_i->remote_conds));
 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
-											   fpinfo_o->remote_conds);
+										  list_copy(fpinfo_o->remote_conds));
 			break;
 
 		case JOIN_LEFT:
 			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
-											  fpinfo_i->remote_conds);
+										  list_copy(fpinfo_i->remote_conds));
 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
-											   fpinfo_o->remote_conds);
+										  list_copy(fpinfo_o->remote_conds));
 			break;
 
 		case JOIN_RIGHT:
 			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
-											  fpinfo_o->remote_conds);
+										  list_copy(fpinfo_o->remote_conds));
 			fpinfo->remote_conds = list_concat(fpinfo->remote_conds,
-											   fpinfo_i->remote_conds);
+										  list_copy(fpinfo_i->remote_conds));
 			break;
 
 		case JOIN_FULL:
 			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
-											  fpinfo_i->remote_conds);
+										  list_copy(fpinfo_i->remote_conds));
 			fpinfo->joinclauses = list_concat(fpinfo->joinclauses,
-											  fpinfo_o->remote_conds);
+										  list_copy(fpinfo_o->remote_conds));
 			break;
 
 		default: