--- ray/src/gen/gensky.c	1989/02/02 11:16:29	1.1
+++ ray/src/gen/gensky.c	1990/03/12 09:49:25	1.3
@@ -133,6 +133,8 @@ computesky()			/* compute sky parameters */
 			zenithbr = (1.376*turbidity-1.81)*tan(altitude)+0.38;
 			zenithbr *= 1000.0/683.0;
 		}
+	if (zenithbr < 0.0)
+		zenithbr = 0.0;
 					/* Compute horizontal radiance */
 	if (cloudy) {
 		groundbr = zenithbr*0.777778;
@@ -157,8 +159,6 @@ computesky()			/* compute sky parameters */
 
 printsky()			/* print out sky */
 {
-	register int  i;
-
 	if (dosun) {
 		printf("\nvoid light solar\n");
 		printf("0\n0\n");