diff --git a/simd-mandelbrot/mandelbrot-worker.js b/simd-mandelbrot/mandelbrot-worker.js
index b89d39c..0717369 100644
--- a/simd-mandelbrot/mandelbrot-worker.js
+++ b/simd-mandelbrot/mandelbrot-worker.js
@@ -49,40 +49,27 @@ function mandelx4(c_re4, c_im4) {
   var four4  = SIMD.Float32x4.splat (4.0);
   var two4   = SIMD.Float32x4.splat (2.0);
   var count4 = SIMD.Int32x4.splat (0);
+  var zero4  = SIMD.Int32x4.splat (0);
   var one4   = SIMD.Int32x4.splat (1);
 
   for (var i = 0; i < max_iterations; ++i) {
     var z_re24 = SIMD.Float32x4.mul (z_re4, z_re4);
     var z_im24 = SIMD.Float32x4.mul (z_im4, z_im4);
 
-    var mi4Tmp = SIMD.Float32x4.lessThanOrEqual (SIMD.Float32x4.add (z_re24, z_im24), four4);
+    var mb4    = SIMD.Float32x4.lessThanOrEqual (SIMD.Float32x4.add (z_re24, z_im24), four4);
     // if all 4 values are greater than 4.0, there's no reason to continue
-    if(!SIMD.Bool32x4.anyTrue(mi4Tmp)) {
+    if (!SIMD.Bool32x4.allTrue(mb4)) {
       break;
     }
 
-    var mi4 = SIMD.Int32x4.splat(4);
-    for(var j=0; j < 4; j++) {
-      switch (SIMD.Bool32x4.extractLane(mi4Tmp, j)) {
-        case true:
-          mi4 = SIMD.Int32x4.replaceLane(mi4, j, -1);
-        break;
-        case false:
-          mi4 = SIMD.Int32x4.replaceLane(mi4, j, 0);
-        break;
-        default:
-          return false;
-        break;
-      }
-    }
-
-    var new_re4 = SIMD.Float32x4.sub (z_re24, z_im24);
-    var new_im4 = SIMD.Float32x4.mul (SIMD.Float32x4.mul (two4, z_re4), z_im4);
-    z_re4       = SIMD.Float32x4.add (c_re4, new_re4);
-    z_im4       = SIMD.Float32x4.add (c_im4, new_im4);
-    count4      = SIMD.Int32x4.add (count4, SIMD.Int32x4.and (mi4, one4));
+    var new_re4 = SIMD.Float32x4.sub(z_re24, z_im24);
+    var new_im4 = SIMD.Float32x4.mul(SIMD.Float32x4.mul (two4, z_re4), z_im4);
+    z_re4       = SIMD.Float32x4.add(c_re4, new_re4);
+    z_im4       = SIMD.Float32x4.add(c_im4, new_im4);
+    count4      = SIMD.Int32x4.add(count4, SIMD.Int32x4.select(mb4, one4, zero4));
   }
   return count4;
+
 }
 
 function mapColorAndSetPixel (x, y, value) {