--- ray/src/util/rpiece.c	2004/10/23 18:55:53	2.45
+++ ray/src/util/rpiece.c	2007/08/22 17:49:54	2.46
@@ -1,5 +1,5 @@
 #ifndef lint
-static const char	RCSid[] = "$Id: rpiece.c,v 2.45 2004/10/23 18:55:53 schorsch Exp $";
+static const char	RCSid[] = "$Id: rpiece.c,v 2.46 2007/08/22 17:49:54 greg Exp $";
 #endif
 /*
  * Generate sections of a picture.
@@ -248,6 +248,10 @@ init(			/* set up output file and start rpict */
 					/* compute piece size */
 	hres /= hmult;
 	vres /= vmult;
+	if (hres <= 0 || vres <= 0) {
+		fprintf(stderr, "%s: illegal resolution/subdivision\n");
+		exit(1);
+	}
 	normaspect(viewaspect(&ourview)*hmult/vmult, &pixaspect, &hres, &vres);
 	sprintf(hrbuf, "%d", hres);
 	rpargv[rpargc++] = "-x"; rpargv[rpargc++] = hrbuf;