diff --git a/index.js b/index.js
index 36da98c..feae75d 100644
--- a/index.js
+++ b/index.js
@@ -1,6 +1,7 @@
 exports.Client = Client
 exports.Server = Server
 
+var bignum = require('bignum')
 var bncode = require('bncode')
 var compact2string = require('compact2string')
 var dgram = require('dgram')
@@ -225,9 +226,9 @@ Client.prototype._requestUdp = function (announceUrl, opts) {
       transactionId,
       self._infoHash,
       self._peerId,
-      toUInt32(0), toUInt32(opts.downloaded || 0), // 64bit
-      toUInt32(0), toUInt32(opts.left || 0), // 64bit
-      toUInt32(0), toUInt32(opts.uploaded || 0), // 64bit
+      toUInt64(opts.downloaded || 0),
+      toUInt64(opts.left || 0),
+      toUInt64(opts.uploaded || 0),
       toUInt32(EVENTS[opts.event] || 0),
       toUInt32(0), // ip address (optional)
       toUInt32(0), // key (optional)
@@ -520,6 +521,10 @@ function toUInt32 (n) {
   return buf
 }
 
+function toUInt64 (n) {
+  return bignum(n).toBuffer({ size: 8 })
+}
+
 function bytewiseEncodeURIComponent (buf) {
   return encodeURIComponent(buf.toString('binary'))
 }
diff --git a/package.json b/package.json
index e2c9c86..ccaee16 100644
--- a/package.json
+++ b/package.json
@@ -11,6 +11,7 @@
     "url": "https://github.com/feross/bittorrent-tracker/issues"
   },
   "dependencies": {
+    "bignum": "^0.6.2",
     "bncode": "^0.5.2",
     "compact2string": "^1.2.0",
     "extend.js": "0.0.1",
diff --git a/test/client-large-torrent.js b/test/client-large-torrent.js
index 1bf1e05..62c5f03 100644
--- a/test/client-large-torrent.js
+++ b/test/client-large-torrent.js
@@ -8,6 +8,9 @@ var parsedTorrent = parseTorrent(torrent)
 var peerId = new Buffer('01234567890123456789')
 var port = 6881
 
+// remove all tracker servers except a single UDP one, for now
+parsedTorrent.announce = [ 'udp://tracker.publicbt.com:80/announce' ]
+
 test('client.start()', function (t) {
   t.plan(4)
 
@@ -18,7 +21,7 @@ test('client.start()', function (t) {
   })
 
   client.once('update', function (data) {
-    t.equal(data.announce, 'http://t.bitlove.org/announce')
+    t.equal(data.announce, 'udp://tracker.publicbt.com:80/announce')
     t.equal(typeof data.complete, 'number')
     t.equal(typeof data.incomplete, 'number')
   })
diff --git a/test/server.js b/test/server.js
index 48f7579..b207b92 100644
--- a/test/server.js
+++ b/test/server.js
@@ -3,6 +3,9 @@ var portfinder = require('portfinder')
 var Server = require('../').Server
 var test = require('tape')
 
+// TODO: add tests to verify that the correct downloaded/left/uploaded numbers are
+// being sent
+
 var infoHash = '4cb67059ed6bd08362da625b3ae77f6f4a075705'
 var peerId = '12345678901234567890'
 var torrentLength = 50000