--- nodeop.c.orig	Tue Mar 15 18:15:58 1994
+++ nodeop.c	Wed Jun  6 15:03:28 2001
@@ -142,7 +142,8 @@
 
     /* for each child */
 	for(np = nodep->child; NODE_NULL != np; np = np->peer){
-		double height = h * np->size / nodep->size;
+		/* When nodep->size is 0, 'divided by zero' will be raised */
+		double height = (nodep->size != 0 ? h * np->size / nodep->size : 0);
 
 		drawrect(np, y, height, depth);