diff --git a/.gitignore b/.gitignore
index 7fc04fe..a6c0ab8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 coverage
 node_modules
 .nyc_output
+npm-debug.log
diff --git a/package.json b/package.json
index 7f6bb52..bba1e9f 100644
--- a/package.json
+++ b/package.json
@@ -60,6 +60,7 @@
     "ecurve": "^1.0.0",
     "randombytes": "^2.0.1",
     "typeforce": "^1.8.7",
+    "varuint-bitcoin": "^1.0.4",
     "wif": "^2.0.1"
   },
   "devDependencies": {
diff --git a/src/bufferutils.js b/src/bufferutils.js
index 458a1e7..bd5f278 100644
--- a/src/bufferutils.js
+++ b/src/bufferutils.js
@@ -1,12 +1,5 @@
 var opcodes = require('./opcodes.json')
-
-// https://github.com/feross/buffer/blob/master/index.js#L1127
-function verifuint (value, max) {
-  if (typeof value !== 'number') throw new Error('cannot write a non-number as a number')
-  if (value < 0) throw new Error('specified a negative value for writing an unsigned value')
-  if (value > max) throw new Error('value is larger than maximum value for type')
-  if (Math.floor(value) !== value) throw new Error('value has a fractional component')
-}
+var varuint = require('varuint-bitcoin')
 
 function pushDataSize (i) {
   return i < opcodes.OP_PUSHDATA1 ? 1
@@ -52,6 +45,14 @@ function readPushDataInt (buffer, offset) {
   }
 }
 
+// https://github.com/feross/buffer/blob/master/index.js#L1127
+function verifuint (value, max) {
+  if (typeof value !== 'number') throw new Error('cannot write a non-number as a number')
+  if (value < 0) throw new Error('specified a negative value for writing an unsigned value')
+  if (value > max) throw new Error('RangeError: value out of range')
+  if (Math.floor(value) !== value) throw new Error('value has a fractional component')
+}
+
 function readUInt64LE (buffer, offset) {
   var a = buffer.readUInt32LE(offset)
   var b = buffer.readUInt32LE(offset + 4)
@@ -62,37 +63,6 @@ function readUInt64LE (buffer, offset) {
   return b + a
 }
 
-function readVarInt (buffer, offset) {
-  var t = buffer.readUInt8(offset)
-  var number, size
-
-  // 8 bit
-  if (t < 253) {
-    number = t
-    size = 1
-
-  // 16 bit
-  } else if (t < 254) {
-    number = buffer.readUInt16LE(offset + 1)
-    size = 3
-
-  // 32 bit
-  } else if (t < 255) {
-    number = buffer.readUInt32LE(offset + 1)
-    size = 5
-
-  // 64 bit
-  } else {
-    number = readUInt64LE(buffer, offset + 1)
-    size = 9
-  }
-
-  return {
-    number: number,
-    size: size
-  }
-}
-
 function writePushDataInt (buffer, number, offset) {
   var size = pushDataSize(number)
 
@@ -126,45 +96,20 @@ function writeUInt64LE (buffer, value, offset) {
   buffer.writeUInt32LE(Math.floor(value / 0x100000000), offset + 4)
 }
 
-function varIntSize (i) {
-  return i < 253 ? 1
-  : i < 0x10000 ? 3
-  : i < 0x100000000 ? 5
-  : 9
-}
+// TODO: remove in 4.0.0?
+function readVarInt (buffer, offset) {
+  var result = varuint.decode(buffer, offset)
 
-function writeVarInt (buffer, number, offset) {
-  var size = varIntSize(number)
-
-  // 8 bit
-  if (size === 1) {
-    buffer.writeUInt8(number, offset)
-
-  // 16 bit
-  } else if (size === 3) {
-    buffer.writeUInt8(253, offset)
-    buffer.writeUInt16LE(number, offset + 1)
-
-  // 32 bit
-  } else if (size === 5) {
-    buffer.writeUInt8(254, offset)
-    buffer.writeUInt32LE(number, offset + 1)
-
-  // 64 bit
-  } else {
-    buffer.writeUInt8(255, offset)
-    writeUInt64LE(buffer, number, offset + 1)
+  return {
+    number: result,
+    size: varuint.decode.bytes
   }
-
-  return size
 }
 
-function varIntBuffer (i) {
-  var size = varIntSize(i)
-  var buffer = new Buffer(size)
-  writeVarInt(buffer, i, 0)
-
-  return buffer
+// TODO: remove in 4.0.0?
+function writeVarInt (buffer, number, offset) {
+  varuint.encode(number, buffer, offset)
+  return varuint.encode.bytes
 }
 
 module.exports = {
@@ -172,13 +117,9 @@ module.exports = {
   readPushDataInt: readPushDataInt,
   readUInt64LE: readUInt64LE,
   readVarInt: readVarInt,
-  varIntBuffer: varIntBuffer,
-  varIntSize: varIntSize,
+  varIntBuffer: varuint.encode,
+  varIntSize: varuint.encodingLength,
   writePushDataInt: writePushDataInt,
   writeUInt64LE: writeUInt64LE,
-  writeVarInt: writeVarInt,
-
-  // TODO: remove in 3.0.0
-  equal: function BufferEquals (a, b) { return a.equals(b) },
-  reverse: require('buffer-reverse')
+  writeVarInt: writeVarInt
 }
diff --git a/test/bufferutils.js b/test/bufferutils.js
index 484bf4f..3a780a7 100644
--- a/test/bufferutils.js
+++ b/test/bufferutils.js
@@ -6,25 +6,6 @@ var bufferutils = require('../src/bufferutils')
 var fixtures = require('./fixtures/bufferutils.json')
 
 describe('bufferutils', function () {
-  // TODO: remove
-  describe('equals', function () {
-    it('works', function () {
-      var a = new Buffer('abcd', 'hex')
-      var b = new Buffer('bbbb', 'hex')
-
-      assert.strictEqual(bufferutils.equal(a, a), true)
-      assert.strictEqual(bufferutils.equal(a, b), false)
-    })
-  })
-
-  describe('reverse', function () {
-    it('works', function () {
-      var a = new Buffer('abcd', 'hex')
-
-      assert.strictEqual(bufferutils.reverse(a).toString('hex'), 'cdab')
-    })
-  })
-
   describe('pushDataSize', function () {
     fixtures.valid.forEach(function (f) {
       it('determines the pushDataSize of ' + f.dec + ' correctly', function () {
diff --git a/test/fixtures/bufferutils.json b/test/fixtures/bufferutils.json
index db1e1da..2b884cf 100644
--- a/test/fixtures/bufferutils.json
+++ b/test/fixtures/bufferutils.json
@@ -86,14 +86,14 @@
     "readUInt64LE": [
       {
         "description": "n === 2^53",
-        "exception": "value is larger than maximum value for type",
+        "exception": "RangeError: value out of range",
         "hex64": "0000000000002000",
         "hexVI": "ff0000000000000020",
         "dec": 9007199254740992
       },
       {
         "description": "n > 2^53",
-        "exception": "value is larger than maximum value for type",
+        "exception": "RangeError: value out of range",
         "hex64": "0100000000002000",
         "hexVI": "ff0100000000000020",
         "dec": 9007199254740993