  In a previous paper [Homology cylinders: an enlargement of the mapping class
group, Algebr. Geom. Topol. 1 (2001) 243--270, arXiv:math.GT/0010247], a group
H_g of homology cylinders over the oriented surface of genus g is defined. A
filtration of H_g is defined, using the Goussarov-Habiro notion of finite-type.
It is erroneously claimed that this filtration essentially coincides with the
relative weight filtration. The present note corrects this error and studies
the actual relation between the two filtrations.
