Set unit for glaces value of memswap free

My Pi has only 100 MB swap (which was default) configured.
I’m using glances to watch my system. But the value of swap space is reported in GB, which results in a yes or no value (0,0 GB till nearly full, that 0.1 GB).

Is there a way to get this value in instead?
(Yes, I know that there is a REST option, but the sensor is already there and before creating another sensor, I would prefer to modify an existing one)