Can't dynamically set 'long_query_time'

MariaDB [(none)]> SET GLOBAL long_query_time=1.000000;

Query OK, 0 rows affected (0.005 sec)

MariaDB [(none)]> SHOW VARIABLES LIKE 'long_query_time';

+-----------------+-----------+

| Variable_name   | Value     |

+-----------------+-----------+

| long_query_time | 10.000000 |

+-----------------+-----------+

1 row in set (0.002 sec)