diff --git a/src/backend/catalog/partition.c b/src/backend/catalog/partition.c
index 832049c..45d95a8 100644
--- a/src/backend/catalog/partition.c
+++ b/src/backend/catalog/partition.c
@@ -1274,7 +1274,7 @@ make_partition_op_expr(PartitionKey key, int keynum,
 				saopexpr->opno = operoid;
 				saopexpr->opfuncid = get_opcode(operoid);
 				saopexpr->useOr = true;
-				saopexpr->inputcollid = key->partcollation[0];
+				saopexpr->inputcollid = key->partcollation[keynum];
 				saopexpr->args = list_make2(arg1, arg2);
 				saopexpr->location = -1;