Selecting multiple fields in QGIS Modeler

I am trying to make a model in the Processing Modeler of QGIS.
I need a step where a layer with polygons is dissolved based on two fields.

At the moment I do this manually. When I open the dissolve algorithm i can select the two fields.

In the modeler version I get a drop down menu or the option to enter the fields. If I try one field, all works well, If I try two fields, the algorithm dissolves my polygon layer as if I didn’t enter any field to dissolve on.

I am almost sure there is something wrong in the notation of how I give in the two field. It is not mentioned in the help document. I must have tried any combination I can think of, but not the correct one.

Does anybody have the answer?

DRVAL1;DRVAL2