diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 0b9a5415..871c7574 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -35,6 +35,7 @@ Marius Eriksen <marius.eriksen@gmail.com>
 Martin Neubauer <m.ne@gmx.net>
 Mathieu Lonjaret <lejatorn@gmail.com>
 Mathieu Lonjaret <mathieu.lonjaret@gmail.com>
+Michael Stroucken <mxs@cmu.edu>
 Michael Teichgräber <mt4swm@googlemail.com>
 Michael Teichgräber <mt@ib.wmipf.de>
 Nathaniel W Filardo <nwf@cs.jhu.edu> <nwfilardo@gmail.com>
diff --git a/src/cmd/venti/srv/png.c b/src/cmd/venti/srv/png.c
index ca456415..8805ada4 100644
--- a/src/cmd/venti/srv/png.c
+++ b/src/cmd/venti/srv/png.c
@@ -212,7 +212,7 @@ writepng(Hio *io, Memimage *m)
 	/* image data */
 	zr.dx = Dx(m->r);
 	zr.dy = Dy(m->r);
-	zr.width = rgb->width * sizeof(ulong);
+	zr.width = rgb->width * sizeof(u32int);
 	zr.data = rgb->data->bdata;
 	zr.x = 0;
 	zr.y = 0;