diff --git a/mysql-test/r/alter_table.result b/mysql-test/r/alter_table.result
index c88abd9867e..2455bc4f997 100644
--- a/mysql-test/r/alter_table.result
+++ b/mysql-test/r/alter_table.result
@@ -1925,8 +1925,8 @@ ALTER TABLE ti1 FORCE;
 affected rows: 0
 info: Records: 0  Duplicates: 0  Warnings: 0
 ALTER TABLE tm1 FORCE;
-affected rows: 0
-info: Records: 0  Duplicates: 0  Warnings: 0
+affected rows: 2
+info: Records: 2  Duplicates: 0  Warnings: 0
 ALTER TABLE ti1 AUTO_INCREMENT 3;
 affected rows: 0
 info: Records: 0  Duplicates: 0  Warnings: 0
diff --git a/mysql-test/r/partition_alter.result b/mysql-test/r/partition_alter.result
index 76b55cefb07..bc2c2f17c97 100644
--- a/mysql-test/r/partition_alter.result
+++ b/mysql-test/r/partition_alter.result
@@ -83,6 +83,8 @@ partition p2 values less than ('2020-10-19'));
 insert t1 values (0, '2000-01-02', 0);
 insert t1 values (1, '2020-01-02', 10);
 alter table t1 add check (b in (0, 1));
+ERROR 23000: CONSTRAINT `CONSTRAINT_1` failed for `test`.`#sql-temporary`
+alter table t1 add check (b in (0, 10));
 show create table t1;
 Table	Create Table
 t1	CREATE TABLE `t1` (
@@ -90,7 +92,7 @@ t1	CREATE TABLE `t1` (
   `d` date NOT NULL,
   `b` tinyint(1) NOT NULL DEFAULT 0,
   PRIMARY KEY (`id`,`d`),
-  CONSTRAINT `CONSTRAINT_1` CHECK (`b` in (0,1))
+  CONSTRAINT `CONSTRAINT_1` CHECK (`b` in (0,10))
 ) ENGINE=MyISAM DEFAULT CHARSET=latin1
  PARTITION BY RANGE  COLUMNS(d)
 (PARTITION p1 VALUES LESS THAN ('2016-10-18') ENGINE = MyISAM,
diff --git a/mysql-test/t/partition_alter.test b/mysql-test/t/partition_alter.test
index 9194e9a8222..e320efcefb9 100644
--- a/mysql-test/t/partition_alter.test
+++ b/mysql-test/t/partition_alter.test
@@ -96,8 +96,10 @@ partition p1 values less than ('2016-10-18'),
 partition p2 values less than ('2020-10-19'));
 insert t1 values (0, '2000-01-02', 0);
 insert t1 values (1, '2020-01-02', 10);
-# FIXME: MDEV-12923 MyISAM allows CHECK constraint violation in ALTER TABLE
+--replace_regex /#sql-[0-9a-f_]*/#sql-temporary/
+--error ER_CONSTRAINT_FAILED
 alter table t1 add check (b in (0, 1));
+alter table t1 add check (b in (0, 10));
 show create table t1;
 --error ER_CONSTRAINT_FAILED
 insert t1 values (2, '2020-01-03', 20);
diff --git a/storage/myisam/ha_myisam.cc b/storage/myisam/ha_myisam.cc
index 77d098cd9f1..28c60308ce9 100644
--- a/storage/myisam/ha_myisam.cc
+++ b/storage/myisam/ha_myisam.cc
@@ -2291,16 +2291,19 @@ ha_myisam::check_if_supported_inplace_alter(TABLE *new_table,
 {
   DBUG_ENTER("ha_myisam::check_if_supported_inplace_alter");
 
-  const uint readd_index= Alter_inplace_info::ADD_INDEX |
+  const Alter_inplace_info::HA_ALTER_FLAGS readd_index=
+                          Alter_inplace_info::ADD_INDEX |
                           Alter_inplace_info::DROP_INDEX;
-  const uint readd_unique= Alter_inplace_info::ADD_UNIQUE_INDEX |
-                           Alter_inplace_info::DROP_UNIQUE_INDEX;
-  const uint readd_pk= Alter_inplace_info::ADD_PK_INDEX |
-                       Alter_inplace_info::DROP_PK_INDEX;
+  const Alter_inplace_info::HA_ALTER_FLAGS readd_unique=
+                          Alter_inplace_info::ADD_UNIQUE_INDEX |
+                          Alter_inplace_info::DROP_UNIQUE_INDEX;
+  const Alter_inplace_info::HA_ALTER_FLAGS readd_pk=
+                          Alter_inplace_info::ADD_PK_INDEX |
+                          Alter_inplace_info::DROP_PK_INDEX;
 
-  const uint op= alter_info->handler_flags;
+  const  Alter_inplace_info::HA_ALTER_FLAGS op= alter_info->handler_flags;
 
-  if (alter_info->handler_flags & Alter_inplace_info::ALTER_COLUMN_VCOL)
+  if (op & Alter_inplace_info::ALTER_COLUMN_VCOL)
     DBUG_RETURN(HA_ALTER_INPLACE_NOT_SUPPORTED);
 
   /*