diff --git a/julia.c b/julia.c
index 138c6b9..7b5871c 100644
--- a/julia.c
+++ b/julia.c
@@ -203,7 +203,10 @@ julia_main(int argc, char *argv[])
 	if (do_light) {
 		long double angle_xy, angle_z;
 		angle_xy = drand48() * 2.0L * RADIAN;
-		angle_z = (0.2L + 0.6L * drand48()) * RADIAN;
+		do
+			angle_z = drand48();
+		while (angle_z == 0.0L || angle_z == 1.0L);
+		angle_z = angle_z * 0.5L * RADIAN;
 		light_x = cosl(angle_xy) * sinl(angle_z);
 		light_y = sinl(angle_xy) * sinl(angle_z);
 		light_z = cosl(angle_z);