diff --git a/src/bin/envmap/perlin.wgsl b/src/bin/envmap/perlin.wgsl
index b07bb7c..e845b49 100644
--- a/src/bin/envmap/perlin.wgsl
+++ b/src/bin/envmap/perlin.wgsl
@@ -137,12 +137,12 @@ fn rand_float(state: ptr<function, u32>) -> f32 {
 }
 
 fn rand_sphere(state: ptr<function, u32>) -> vec3f {
-	loop {
+	for (var k = 0; k < 16; k++) {
 		let v = vec3f(rand_float(state), rand_float(state), rand_float(state)) - 0.5;
 		let l = length(v);
 		if (length(v) <= 0.5) {
 			return v / l;
 		}
 	}
-	return vec3f(0.0); // unreachable
+	return vec3f(0.0); // safeguard
 }