Index: draw_wireframe.h
===================================================================
--- draw_wireframe.h	(revision 12351)
+++ draw_wireframe.h	(revision 12352)
@@ -84,8 +84,18 @@
 		else
 			pcb_gui->draw_line(gc, x1, y1, x2, y2);
 	}
-	else
+	else {
+		if (square) {
+			/* square cap 0 long line does not have an angle -> always draw it axis aligned */
+			pcb_coord_t cx1 = x1 - thick/2, cx2 = x1 + thick/2, cy1 = y1 - thick/2, cy2 = y1 + thick/2;
+			pcb_gui->draw_line(gc, cx1, cy1, cx2, cy1);
+			pcb_gui->draw_line(gc, cx2, cy1, cx2, cy2);
+			pcb_gui->draw_line(gc, cx2, cy2, cx1, cy2);
+			pcb_gui->draw_line(gc, cx1, cy2, cx1, cy1);
+		}
+		else
 			pcb_gui->draw_arc(gc, x1, y1, thick/2, thick/2, 0, 360); 
+	}
 }
 
 #endif /* ! defined PCB_DRAW_WIREFRAME_H */