diff --git a/ddl/db_partition_test.go b/ddl/db_partition_test.go
index c0e087ef4a046..1de6628cce895 100644
--- a/ddl/db_partition_test.go
+++ b/ddl/db_partition_test.go
@@ -4535,6 +4535,22 @@ func TestPartitionTableWithAnsiQuotes(t *testing.T) {
 		` PARTITION "p4" VALUES LESS THAN ('\\''\t\n','\\''\t\n'),` + "\n" +
 		` PARTITION "pMax" VALUES LESS THAN (MAXVALUE,MAXVALUE))`))
 }
+
+func TestAlterModifyPartitionColTruncateWarning(t *testing.T) {
+	store := testkit.CreateMockStore(t)
+	tk := testkit.NewTestKit(t, store)
+	schemaName := "truncWarn"
+	tk.MustExec("create database " + schemaName)
+	tk.MustExec("use " + schemaName)
+	tk.MustExec(`set sql_mode = default`)
+	tk.MustExec(`create table t (a varchar(255)) partition by range columns (a) (partition p1 values less than ("0"), partition p2 values less than ("zzzz"))`)
+	tk.MustExec(`insert into t values ("123456")`)
+	tk.MustContainErrMsg(`alter table t modify a varchar(5)`, "[types:1265]Data truncated for column 'a', value is '123456'")
+	tk.MustExec(`set sql_mode = ''`)
+	tk.MustExec(`alter table t modify a varchar(5)`)
+	tk.MustQuery(`show warnings`).Check(testkit.Rows())
+}
+
 func TestAlterModifyColumnOnPartitionedTable(t *testing.T) {
 	store := testkit.CreateMockStore(t)
 	tk := testkit.NewTestKit(t, store)