Use of NOW() in SQL statement results in out-of-range SQL error, preventing sensor discovery

I am running the latest community edition (17.9.0), but recently when adding a new host I noticed that CPU temperatures etc from lm_sensors were not being discovered by Observium. Running discovery.php in debug mode revealed that although they were being discovered, the sensor creation in the database was failing because the NOW() function in the SQL query returned a value that is out of the range of the sensor_polled column. NOW() returns a human readable value (e.g. '2018-08-26 18:21:15' or '20180826182107' in a numeric context), whereas the sensor_polled column is an int(11) column that appears to hold UNIX timestamps. Should the query switch to using the UNIX_TIMESTAMP() SQL function instead of NOW()?

SQL[INSERT INTO `sensors` (`poller_type`,`sensor_class`,`device_id`,`sensor_index`,`sensor_type`,`sensor_oid`,`sensor_descr`,`sensor_multiplier`,`sensor_deleted`,`sensor_limit`,`sensor_limit_warn`,`sensor_limit_low`,`sensor_limit_low_warn`,`entPhysicalIndex`,`entPhysicalClass`,`entPhysicalIndex_measured`,`measured_class`,`measured_entity`,`sensor_unit`,`sensor_value`,`sensor_polled`)  VALUES ('snmp','temperature','48','5','lmsensors','.1.3.6.1.4.1.2021.13.16.2.1.3.5','Core 1','0.001','0','49.6',NULL,'0',NULL,NULL,NULL,NULL,NULL,NULL,NULL,'31',NOW())]

SQL RUNTIME[0.00026822s]

ERROR[Error in query: (Out of range value for column 'sensor_polled' at row 1) 1264]

(  inserted )