Index: pcb_draw.c
===================================================================
--- pcb_draw.c	(revision 7408)
+++ pcb_draw.c	(revision 7409)
@@ -111,6 +111,12 @@
 		ay = y < 0 ? -y : y;
 		x1 = xc - pa[ay];
 		x2 = xc + pa[ay];
+		if (x1 >= dst->sx)
+			continue;
+		if (x1 < 0)
+			x1 = 0;
+		if (x2 >= dst->sy)
+			x2 = dst->sy;
 		p = &image_pix(dst, x1, y+yc);
 		for(x = x1; x <= x2; x++,p++) {
 			*p = pixel_black;