diff --git a/ddl/multi_schema_change.go b/ddl/multi_schema_change.go
index f7a5d552eb..c99c93402e 100644
--- a/ddl/multi_schema_change.go
+++ b/ddl/multi_schema_change.go
@@ -333,7 +333,7 @@ func mergeAddIndex(info *model.MultiSchemaInfo) {
 			// Foreign key requires the order of adding indexes is unchanged.
 			return
 		}
-		if subJob.Type == model.ActionAddIndex {
+		if subJob.Type == model.ActionAddIndex || subJob.Type == model.ActionAddPrimaryKey {
 			if i == 0 {
 				consistentUnique = subJob.Args[0].(bool)
 			} else {
diff --git a/ddl/multi_schema_change_test.go b/ddl/multi_schema_change_test.go
index 65c132ddbc..89a469c5c3 100644
--- a/ddl/multi_schema_change_test.go
+++ b/ddl/multi_schema_change_test.go
@@ -1223,6 +1223,21 @@ func TestMultiSchemaChangeAddIndexChangeColumn(t *testing.T) {
 	tk.MustExec("admin check table t;")
 }
 
+func TestMultiSchemaChangeAddIndexOrder(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	tk.MustExec("use test;")
+	tk.MustExec("create table t (a int);")
+	tk.MustExec("insert into t values (123);")
+	tk.MustExec("alter table t add index i(a), add primary key (a);")
+	result := "t CREATE TABLE `t` (\n" +
+		"  `a` int(11) NOT NULL,\n" +
+		"  KEY `i` (`a`),\n" +
+		"  PRIMARY KEY (`a`) /*T![clustered_index] NONCLUSTERED */\n" +
+		") ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_bin"
+	tk.MustQuery("show create table t;").Check(testkit.Rows(result))
+}
+
 func TestMultiSchemaChangeMixedWithUpdate(t *testing.T) {
 	store, dom := testkit.CreateMockStoreAndDomain(t)
 	tk := testkit.NewTestKit(t, store)