Index: trunk/psphot/src/psphotAddNoise.c
===================================================================
--- trunk/psphot/src/psphotAddNoise.c	(revision 18000)
+++ trunk/psphot/src/psphotAddNoise.c	(revision 18001)
@@ -69,4 +69,8 @@
         oldshape.sxy = PAR[PM_PAR_SXY];
 
+	// XXX can this be done more intelligently?
+	if (oldI0 == 0.0) continue;
+	if (!isfinite(oldI0)) continue;
+
         // increase size and height of source
         axes = psEllipseShapeToAxes (oldshape, 20.0);