diff --git a/png.js b/png.js
index 442bba5..2060ee9 100644
--- a/png.js
+++ b/png.js
@@ -301,7 +301,7 @@
       var c, i, length, palette, pos, ret, transparency, _i, _ref, _ref1;
       palette = this.palette;
       transparency = this.transparency.indexed || [];
-      ret = new Uint8Array((transparency.length || 0) + palette.length);
+      ret = new Uint8Array((transparency.length || palette.length/3) + palette.length);
       pos = 0;
       length = palette.length;
       c = 0;