De Jansmolen or De Modden is a Hollow Post mill in Goëngahuizen, Friesland, Netherlands which has been restored as a landscape feature.

During the summer it drained an area of 200 pondemaat (73 ha; 180 acres) and during the winter it drained an area of 60 pondemaat (22 ha; 54 acres).

[2] De Jansmolen is what the Dutch describe as an spinnenkop.

It is a hollow post mill on a single-storey square roundhouse.

The roundhouse is clad in pantiles and mill body is covered in vertical boards, while the roof of the mill is boarded vertically and covered in felt.