Index: trunk/src/thermal.c
===================================================================
--- trunk/src/thermal.c	(revision 12415)
+++ trunk/src/thermal.c	(revision 12416)
@@ -146,24 +146,31 @@
 
 		case PCB_THERMAL_ROUND:
 			if (line->thermal & PCB_THERMAL_DIAGONAL) {
+				/* side clear lines */
 				pa = pa_line_at(
 					x1 - clrth * nx - clr * vx * 0.75, y1 - clrth * ny - clr * vy * 0.75,
 					x2 - clrth * nx + clr * vx * 0.75, y2 - clrth * ny + clr * vy * 0.75,
 					clr);
-
 				pb = pa_line_at(
 					x1 + clrth * nx - clr * vx * 0.75, y1 + clrth * ny - clr * vy * 0.75,
 					x2 + clrth * nx + clr * vx * 0.75, y2 + clrth * ny + clr * vy * 0.75,
 					clr);
-
 				pcb_polyarea_boolean_free(pa, pb, &pc, PCB_PBO_UNITE);
 
+				/* x1;y1 cap arc */
 				pa = pc; pc = NULL;
 				pb = pa_arc_at(x1, y1, clrth,
 					x1 - clrth * nx + clr * vx * 2.0, y1 - clrth * ny + clr * vy * 2.0,
 					x1 + clrth * nx + clr * vx * 2.0, y1 + clrth * ny + clr * vy * 2.0,
 					clr, 180.0);
+				pcb_polyarea_boolean_free(pa, pb, &pc, PCB_PBO_UNITE);
 
+				/* x2;y2 cap arc */
+				pa = pc; pc = NULL;
+				pb = pa_arc_at(x2, y2, clrth,
+					x2 - clrth * nx - clr * vx * 2.0, y2 - clrth * ny - clr * vy * 2.0,
+					x2 + clrth * nx - clr * vx * 2.0, y2 + clrth * ny - clr * vy * 2.0,
+					clr, 180.0);
 				pcb_polyarea_boolean_free(pa, pb, &pc, PCB_PBO_UNITE);
 
 				return pc;