diff --git a/index.html b/index.html
index e4fccd4..b754c32 100644
--- a/index.html
+++ b/index.html
@@ -1,5 +1,6 @@
 <!DOCTYPE html>
 <!-- xlsx.js (C) 2013-2014 SheetJS http://sheetjs.com -->
+<!-- vim: set ts=2: -->
 <html>
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
@@ -37,6 +38,14 @@
 <script src="shim.js"></script>
 <script>
 var rABS = typeof FileReader !== "undefined" && typeof FileReader.prototype !== "undefined" && typeof FileReader.prototype.readAsBinaryString !== "undefined";
+function fixdata(data) {
+	var o = "", l = 0, w = 10240;
+	for(; l<data.byteLength/w; ++l)
+		o+=String.fromCharCode.apply(null,new Uint8Array(data.slice(l*w,l*w+w)));
+	o+=String.fromCharCode.apply(null, new Uint8Array(data.slice(o.length)));
+	return o;
+}
+
 function xlsxworker(data, cb) {
 	var worker = new Worker('./xlsxworker.js');
 	worker.onmessage = function(e) {
@@ -46,7 +55,7 @@ function xlsxworker(data, cb) {
 			case 'xlsx': cb(JSON.parse(e.data.d)); break;
 		}
 	};
-	var arr = rABS ? data : btoa(String.fromCharCode.apply(null, new Uint8Array(data)));
+	var arr = rABS ? data : btoa(fixdata(data));
 	worker.postMessage({d:arr,b:rABS});
 }
 
@@ -110,7 +119,7 @@ function process_wb(wb) {
 			break;
 		case "form":
 			output = to_formulae(wb);
-			break; 
+			break;
 		default:
 		output = to_csv(wb);
 	}
@@ -136,7 +145,7 @@ function handleDrop(e) {
 				if(rABS) {
 					wb = XLSX.read(data, {type: 'binary'});
 				} else {
-					var arr = String.fromCharCode.apply(null, new Uint8Array(data));
+				var arr = fixdata(data);
 					wb = XLSX.read(btoa(arr), {type: 'base64'});
 				}
 				process_wb(wb);
diff --git a/shim.js b/shim.js
index 93264f4..e3569da 100644
--- a/shim.js
+++ b/shim.js
@@ -143,3 +143,31 @@ if (!Array.prototype.map) {
     return A;
   };      
 }
+
+// https://github.com/ttaubert/node-arraybuffer-slice
+// (c) 2013 Tim Taubert <tim@timtaubert.de>
+// arraybuffer-slice may be freely distributed under the MIT license.
+
+"use strict";
+
+if (!ArrayBuffer.prototype.slice) {
+  ArrayBuffer.prototype.slice = function (begin, end) {
+    begin = (begin|0) || 0;
+    var num = this.byteLength;
+    end = end === (void 0) ? num : (end|0);
+
+    // Handle negative values.
+    if (begin < 0) begin += num;
+    if (end < 0) end += num;
+
+    if (num === 0 || begin >= num || begin >= end) {
+      return new ArrayBuffer(0);
+    }
+
+    var length = Math.min(num - begin, end - begin);
+    var target = new ArrayBuffer(length);
+    var targetArray = new Uint8Array(target);
+    targetArray.set(new Uint8Array(this, begin, length));
+    return target;
+  };
+}
