diff --git a/mysql-test/r/old-mode.result b/mysql-test/r/old-mode.result
index 0b10067c19b..b7e1ee26391 100644
--- a/mysql-test/r/old-mode.result
+++ b/mysql-test/r/old-mode.result
@@ -22,6 +22,7 @@ Id	User	Host	db	Command	Time	State	Info
 #
 # MDEV-5372 Make "CAST(time_expr AS DATETIME)" compatible with the SQL Standard)
 #
+set @@old_mode=zero_date_time_cast;
 SELECT CAST(TIME'-10:30:30' AS DATETIME);
 CAST(TIME'-10:30:30' AS DATETIME)
 NULL
diff --git a/mysql-test/suite/sys_vars/r/old_mode_basic.result b/mysql-test/suite/sys_vars/r/old_mode_basic.result
index c9a650e7b15..052221d796e 100644
--- a/mysql-test/suite/sys_vars/r/old_mode_basic.result
+++ b/mysql-test/suite/sys_vars/r/old_mode_basic.result
@@ -111,10 +111,14 @@ SELECT @@global.old_mode;
 @@global.old_mode
 NO_PROGRESS_INFO
 SET @@global.old_mode = 4;
-ERROR 42000: Variable 'old_mode' can't be set to the value of '4'
 SELECT @@global.old_mode;
 @@global.old_mode
-NO_PROGRESS_INFO
+ZERO_DATE_TIME_CAST
+SET @@global.old_mode = 8;
+ERROR 42000: Variable 'old_mode' can't be set to the value of '8'
+SELECT @@global.old_mode;
+@@global.old_mode
+ZERO_DATE_TIME_CAST
 SET @@global.old_mode = 0.4;
 ERROR 42000: Incorrect argument type to variable 'old_mode'
 '#---------------------FN_DYNVARS_152_08----------------------#'
diff --git a/mysql-test/suite/sys_vars/t/old_mode_basic.test b/mysql-test/suite/sys_vars/t/old_mode_basic.test
index 6770219887d..93a93960836 100644
--- a/mysql-test/suite/sys_vars/t/old_mode_basic.test
+++ b/mysql-test/suite/sys_vars/t/old_mode_basic.test
@@ -168,10 +168,13 @@ SELECT @@global.old_mode;
 SET @@global.old_mode = 2;
 SELECT @@global.old_mode;
 
---Error ER_WRONG_VALUE_FOR_VAR
 SET @@global.old_mode = 4;
 SELECT @@global.old_mode;
 
+--Error ER_WRONG_VALUE_FOR_VAR
+SET @@global.old_mode = 8;
+SELECT @@global.old_mode;
+
 # use of decimal values
 
 --Error ER_WRONG_TYPE_FOR_VAR
diff --git a/mysql-test/t/old-mode.test b/mysql-test/t/old-mode.test
index 56916aefd77..483549886db 100644
--- a/mysql-test/t/old-mode.test
+++ b/mysql-test/t/old-mode.test
@@ -29,7 +29,7 @@ SHOW PROCESSLIST;
 --echo #
 --echo # MDEV-5372 Make "CAST(time_expr AS DATETIME)" compatible with the SQL Standard)
 --echo #
-# Checking that "mysqld --old" exposes the 5.5 conversion behaviour
+set @@old_mode=zero_date_time_cast;
 SELECT CAST(TIME'-10:30:30' AS DATETIME);
 SELECT CAST(TIME'10:20:30' AS DATETIME);
 SELECT CAST(TIME'830:20:30' AS DATETIME);
@@ -53,12 +53,12 @@ SELECT a, CAST(a AS DATETIME), TO_DAYS(a) FROM t1;
 DROP TABLE t1;
 # Note, it was actually a bug that TO_DAYS('830:20:30') returned NULL
 # for a column, while 3 for an expression. We won't fix this,
-# it's "mysqld --old" anyway.
+# it's "old_mode" anyway.
 SELECT TO_DAYS(TIME'-10:20:30');
 SELECT TO_DAYS(TIME'10:20:30');
 SELECT TO_DAYS(TIME'830:20:30');
 
-# This is to cover Item_temporal_hybrid_func::fix_temporal_type in --old mode:
+# This is to cover Item_temporal_hybrid_func::fix_temporal_type in old_mode:
 CREATE TABLE t1 (a DATETIME, b TIME);
 INSERT INTO t1 VALUES (NULL, '00:20:12');
 INSERT INTO t1 VALUES (NULL, '-00:20:12');
diff --git a/sql/item.cc b/sql/item.cc
index 1c81fda9c63..0fbd58567ef 100644
--- a/sql/item.cc
+++ b/sql/item.cc
@@ -248,7 +248,8 @@ bool Item::get_date_with_conversion(MYSQL_TIME *ltime, ulonglong fuzzydate)
     and leave it to get_date() to check date.
   */
   ulonglong time_flag= (field_type() == MYSQL_TYPE_TIME &&
-                       !current_thd->variables.old_mode) ? TIME_TIME_ONLY : 0;
+           !(current_thd->variables.old_behavior & OLD_MODE_ZERO_DATE_TIME_CAST)) ?
+           TIME_TIME_ONLY : 0;
   if (get_date(ltime, fuzzydate | time_flag))
     return true;
   if (ltime->time_type == MYSQL_TIMESTAMP_TIME &&
diff --git a/sql/sql_class.h b/sql/sql_class.h
index ef28d860b04..140fe934b44 100644
--- a/sql/sql_class.h
+++ b/sql/sql_class.h
@@ -121,8 +121,9 @@ enum enum_filetype { FILETYPE_CSV, FILETYPE_XML };
 #define MODE_PAD_CHAR_TO_FULL_LENGTH    (1ULL << 31)
 
 /* Bits for different old style modes */
-#define OLD_MODE_NO_DUP_KEY_WARNINGS_WITH_IGNORE	1
-#define OLD_MODE_NO_PROGRESS_INFO			2
+#define OLD_MODE_NO_DUP_KEY_WARNINGS_WITH_IGNORE	(1 << 0)
+#define OLD_MODE_NO_PROGRESS_INFO			(1 << 1)
+#define OLD_MODE_ZERO_DATE_TIME_CAST                    (1 << 2)
 
 extern char internal_table_name[2];
 extern char empty_c_string[1];
diff --git a/sql/sql_time.cc b/sql/sql_time.cc
index 06098094505..2c4998fdf5e 100644
--- a/sql/sql_time.cc
+++ b/sql/sql_time.cc
@@ -1243,7 +1243,7 @@ time_to_datetime_old(THD *thd, const MYSQL_TIME *from, MYSQL_TIME *to)
 bool
 time_to_datetime(THD *thd, const MYSQL_TIME *from, MYSQL_TIME *to)
 {
-  if (thd->variables.old_mode)
+  if (thd->variables.old_behavior & OLD_MODE_ZERO_DATE_TIME_CAST)
     return time_to_datetime_old(thd, from, to);
   set_current_date(thd, to);
   mix_date_and_time(to, from);
@@ -1266,7 +1266,8 @@ time_to_datetime_with_warn(THD *thd,
     only in the old mode.
   */
   if (time_to_datetime(thd, from, to) ||
-      (thd->variables.old_mode && check_date(to, fuzzydate, &warn)))
+      ((thd->variables.old_behavior && OLD_MODE_ZERO_DATE_TIME_CAST) &&
+        check_date(to, fuzzydate, &warn)))
   {
     ErrConvTime str(from);
     make_truncated_value_warning(thd, Sql_condition::WARN_LEVEL_WARN,
@@ -1274,4 +1275,4 @@ time_to_datetime_with_warn(THD *thd,
     return true;
   }
   return false;
-}
\ No newline at end of file
+}
diff --git a/sql/sys_vars.cc b/sql/sys_vars.cc
index 20784ce9301..0324da0ae55 100644
--- a/sql/sys_vars.cc
+++ b/sql/sys_vars.cc
@@ -2876,7 +2876,9 @@ static Sys_var_set Sys_sql_mode(
 
 static const char *old_mode_names[]=
 {
-  "NO_DUP_KEY_WARNINGS_WITH_IGNORE", "NO_PROGRESS_INFO",
+  "NO_DUP_KEY_WARNINGS_WITH_IGNORE",
+  "NO_PROGRESS_INFO",
+  "ZERO_DATE_TIME_CAST",
   0
 };