diff --git a/expression/builtin_time.go b/expression/builtin_time.go
index b661f71818..d8fe5b3971 100644
--- a/expression/builtin_time.go
+++ b/expression/builtin_time.go
@@ -2757,11 +2757,9 @@ func (du *baseDateArithmitical) getDateFromDatetime(ctx sessionctx.Context, args
 		return types.ZeroTime, true, err
 	}
 
-	dateTp := mysql.TypeDate
-	if date.Type() == mysql.TypeDatetime || date.Type() == mysql.TypeTimestamp || types.IsClockUnit(unit) {
-		dateTp = mysql.TypeDatetime
+	if types.IsClockUnit(unit) {
+		date.SetType(mysql.TypeDatetime)
 	}
-	date.SetType(dateTp)
 	return date, false, nil
 }
 
@@ -3030,11 +3028,9 @@ func (du *baseDateArithmitical) vecGetDateFromDatetime(b *baseBuiltinFunc, input
 			continue
 		}
 
-		dateTp := mysql.TypeDate
-		if dates[i].Type() == mysql.TypeDatetime || dates[i].Type() == mysql.TypeTimestamp || isClockUnit {
-			dateTp = mysql.TypeDatetime
+		if isClockUnit {
+			dates[i].SetType(mysql.TypeDatetime)
 		}
-		dates[i].SetType(dateTp)
 	}
 	return nil
 }
diff --git a/expression/integration_test.go b/expression/integration_test.go
index 617aab9ff2..2a86d240b9 100644
--- a/expression/integration_test.go
+++ b/expression/integration_test.go
@@ -7722,6 +7722,15 @@ func (s *testIntegrationSerialSuite) TestClusteredIndexAndNewCollation(c *C) {
 	tk.MustQuery("select * from t").Check(testkit.Rows("&"))
 }
 
+func (s *testIntegrationSuite) TestIssue20860(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t;")
+	tk.MustExec("create table t(id int primary key, c int, d timestamp null default null)")
+	tk.MustExec("insert into t values(1, 2, '2038-01-18 20:20:30')")
+	c.Assert(tk.ExecToErr("update t set d = adddate(d, interval 1 day) where id < 10"), NotNil)
+}
+
 func (s *testIntegrationSerialSuite) TestIssue20608(c *C) {
 	collate.SetNewCollationEnabledForTest(true)
 	defer collate.SetNewCollationEnabledForTest(false)