diff --git a/cid.go b/cid.go
index fb6496e..72e822a 100644
--- a/cid.go
+++ b/cid.go
@@ -29,6 +29,7 @@ import (
 
 	mbase "github.com/multiformats/go-multibase"
 	mh "github.com/multiformats/go-multihash"
+	strbinary "github.com/multiformats/go-multihash/strbinary"
 )
 
 // UnsupportedVersionString just holds an error message
@@ -133,18 +134,18 @@ var CodecToStr = map[uint64]string{
 // compatibility with the plain-multihash format used used in IPFS.
 // NewCidV1 should be used preferentially.
 func NewCidV0(mhash mh.Multihash) Cid {
-	return Cid{string(mhash)}
+	return Cid{mhash.Binary()}
 }
 
 // NewCidV1 returns a new Cid using the given multicodec-packed
 // content type.
 func NewCidV1(codecType uint64, mhash mh.Multihash) Cid {
-	hashlen := len(mhash)
+	hashlen := len(mhash.Binary())
 	// two 8 bytes (max) numbers plus hash
 	buf := make([]byte, 2*binary.MaxVarintLen64+hashlen)
 	n := binary.PutUvarint(buf, 1)
 	n += binary.PutUvarint(buf[n:], codecType)
-	cn := copy(buf[n:], mhash)
+	cn := copy(buf[n:], mhash.Binary())
 	if cn != hashlen {
 		panic("copy hash length is inconsistent")
 	}
@@ -291,12 +292,12 @@ func Cast(data []byte) (Cid, error) {
 	}
 
 	rest := data[n+cn:]
-	h, err := mh.Cast(rest)
+	_, err := mh.FromBinary(string(rest))
 	if err != nil {
 		return Nil, err
 	}
 
-	return Cid{string(data[0 : n+cn+len(h)])}, nil
+	return Cid{string(data)}, nil
 }
 
 // Version returns the Cid version.
@@ -312,8 +313,7 @@ func (c Cid) Type() uint64 {
 	if c.Version() == 0 {
 		return DagProtobuf
 	}
-	_, n := uvarint(c.str)
-	codec, _ := uvarint(c.str[n:])
+	codec, _ := strbinary.Uvarint(c.str[1:])
 	return codec
 }
 
@@ -368,18 +368,18 @@ func (c Cid) Encode(base mbase.Encoder) string {
 
 // Hash returns the multihash contained by a Cid.
 func (c Cid) Hash() mh.Multihash {
-	bytes := c.Bytes()
-
 	if c.Version() == 0 {
-		return mh.Multihash(bytes)
+		h, _ := mh.FromBinary(c.str)
+		return h
 	}
 
-	// skip version length
-	_, n1 := binary.Uvarint(bytes)
-	// skip codec length
-	_, n2 := binary.Uvarint(bytes[n1:])
+	// Skip 1 byte for the version prefix
+	i := 1
+	// Skip the Codec prefix
+	i += strbinary.UvarintLen(c.str[i:])
 
-	return mh.Multihash(bytes[n1+n2:])
+	h, _ := mh.FromBinary(c.str[i:])
+	return h
 }
 
 // Bytes returns the byte representation of a Cid.
@@ -448,10 +448,10 @@ func (c Cid) Loggable() map[string]interface{} {
 
 // Prefix builds and returns a Prefix out of a Cid.
 func (c Cid) Prefix() Prefix {
-	dec, _ := mh.Decode(c.Hash()) // assuming we got a valid multiaddr, this will not error
+	mhType, digest := c.Hash().Parts()
 	return Prefix{
-		MhType:   dec.Code,
-		MhLength: dec.Length,
+		MhType:   mhType,
+		MhLength: len(digest),
 		Version:  c.Version(),
 		Codec:    c.Type(),
 	}
diff --git a/cid_test.go b/cid_test.go
index 1b1e9c4..5151439 100644
--- a/cid_test.go
+++ b/cid_test.go
@@ -1,7 +1,6 @@
 package cid
 
 import (
-	"bytes"
 	"encoding/json"
 	"fmt"
 	"math/rand"
@@ -46,7 +45,7 @@ func assertEqual(t *testing.T, a, b Cid) {
 		t.Fatal("mismatch on version")
 	}
 
-	if !bytes.Equal(a.Hash(), b.Hash()) {
+	if a.Hash() != b.Hash() {
 		t.Fatal("multihash mismatch")
 	}
 }
diff --git a/package.json b/package.json
index 8b821c4..e209910 100644
--- a/package.json
+++ b/package.json
@@ -9,9 +9,9 @@
   "gxDependencies": [
     {
       "author": "whyrusleeping",
-      "hash": "QmPnFwZ2JXKnXgMw8CdBPxn7FWh6LLdjUjxV1fKHuJnkr8",
+      "hash": "QmbdgmS5VjypczPKycTRH9GnyKt6WQLsQERyLUzaJECHh6",
       "name": "go-multihash",
-      "version": "1.0.8"
+      "version": "2.0.0"
     },
     {
       "author": "whyrusleeping",
diff --git a/varint.go b/varint.go
deleted file mode 100644
index 391c1f4..0000000
--- a/varint.go
+++ /dev/null
@@ -1,34 +0,0 @@
-package cid
-
-// Version of varint function that work with a string rather than
-// []byte to avoid unnecessary allocation
-
-// Copyright 2011 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license as given at https://golang.org/LICENSE
-
-// uvarint decodes a uint64 from buf and returns that value and the
-// number of characters read (> 0). If an error occurred, the value is 0
-// and the number of bytes n is <= 0 meaning:
-//
-// 	n == 0: buf too small
-// 	n  < 0: value larger than 64 bits (overflow)
-// 	        and -n is the number of bytes read
-//
-func uvarint(buf string) (uint64, int) {
-	var x uint64
-	var s uint
-	// we have a binary string so we can't use a range loope
-	for i := 0; i < len(buf); i++ {
-		b := buf[i]
-		if b < 0x80 {
-			if i > 9 || i == 9 && b > 1 {
-				return 0, -(i + 1) // overflow
-			}
-			return x | uint64(b)<<s, i + 1
-		}
-		x |= uint64(b&0x7f) << s
-		s += 7
-	}
-	return 0, 0
-}
diff --git a/varint_test.go b/varint_test.go
deleted file mode 100644
index 47bb061..0000000
--- a/varint_test.go
+++ /dev/null
@@ -1,22 +0,0 @@
-package cid
-
-import (
-	"encoding/binary"
-	"testing"
-)
-
-func TestUvarintRoundTrip(t *testing.T) {
-	testCases := []uint64{0, 1, 2, 127, 128, 129, 255, 256, 257, 1<<63 - 1}
-	for _, tc := range testCases {
-		buf := make([]byte, 16)
-		binary.PutUvarint(buf, tc)
-		v, l1 := uvarint(string(buf))
-		_, l2 := binary.Uvarint(buf)
-		if tc != v {
-			t.Errorf("roundtrip failed expected %d but got %d", tc, v)
-		}
-		if l1 != l2 {
-			t.Errorf("length incorrect expected %d but got %d", l2, l1)
-		}
-	}
-}