Index: topoly.c
===================================================================
--- topoly.c	(revision 33222)
+++ topoly.c	(revision 33223)
@@ -403,6 +403,9 @@
 	else
 		poly = pcb_topoly_conn_with(pcb, start, how, df);
 
+	if (poly == NULL)
+		return NULL;
+
 	pcb_poly_bbox(poly);
 	poly->Clipped = pcb_poly_to_polyarea(poly, &need_full);