Index: trunk/src/obj_pinvia_therm.c
===================================================================
--- trunk/src/obj_pinvia_therm.c	(revision 9503)
+++ trunk/src/obj_pinvia_therm.c	(revision 9504)
@@ -315,9 +315,14 @@
 	pcb_polyarea_t *p, *p2, *m;
 	pcb_coord_t t = 0.5 * pcb->ThermScale * pin->Clearance;
 	pcb_coord_t w = pin->Thickness + pin->Clearance;
+	int shape = PCB_FLAG_SQUARE_GET(pin);
 
-	p = pcb_poly_from_octagon(pin->X, pin->Y, w, PCB_FLAG_SQUARE_GET(pin));
-	p2 = pcb_poly_from_octagon(pin->X, pin->Y, pin->Thickness, PCB_FLAG_SQUARE_GET(pin));
+	/* temporary work around corner case on square+octagon shape with large clearance */
+	if (shape <= 1)
+		shape = 17;
+
+	p = pcb_poly_from_octagon(pin->X, pin->Y, w, shape);
+	p2 = pcb_poly_from_octagon(pin->X, pin->Y, pin->Thickness, shape);
 	/* make full clearance ring */
 	pcb_polyarea_boolean_free(p, p2, &m, PCB_PBO_SUB);
 	switch (style) {
Index: trunk/src/polygon.c
===================================================================
--- trunk/src/polygon.c	(revision 9503)
+++ trunk/src/polygon.c	(revision 9504)
@@ -776,6 +776,8 @@
 	else {
 		size = (thick + clear + 1) / 2;
 		if (PCB_FLAG_TEST(PCB_FLAG_OCTAGON, pin)) {
+			if (PCB_FLAG_SQUARE_GET(pin) <= 1)
+				size /= 2;
 			return pcb_poly_from_octagon(pin->X, pin->Y, size + size, PCB_FLAG_SQUARE_GET(pin));
 		}
 	}