client.go         |  2 +-
 global.go         | 17 ++++-------------
 handshake.go      |  7 +++++++
 handshake_test.go |  2 +-

diff --git a/client.go b/client.go
index bab9e5601cabb925b42983552421a15d29f0a368..fbdef7e3c8ecc4326e8de1a5ac43b5fe8e7029cd 100644
--- a/client.go
+++ b/client.go
@@ -278,7 +278,7 @@ 		cl.downloadLimit = rate.NewLimiter(rate.Inf, 0)
 	} else {
 		cl.downloadLimit = cfg.DownloadRateLimiter
 	}
-	missinggo.CopyExact(&cl.extensionBytes, defaultExtensionBytes)
+	cl.extensionBytes = defaultPeerExtensionBytes()
 	cl.event.L = &cl.mu
 	storageImpl := cfg.DefaultStorage
 	if storageImpl == nil {
diff --git a/global.go b/global.go
index 4b27f2e50b7a2e277e57a2a28157ca12c7c7332d..8012fe6155d1361e1b3fd975232896796ebe4f57 100644
--- a/global.go
+++ b/global.go
@@ -10,24 +10,15 @@ 	pieceHash        = crypto.SHA1
 	maxRequests      = 250    // Maximum pending requests we allow peers to send us.
 	defaultChunkSize = 0x4000 // 16KiB
 
-	// Justification for set bits follows.
-	//
-	// Extension protocol ([5]|=0x10):
-	// http://www.bittorrent.org/beps/bep_0010.html
-	//
-	// Fast Extension ([7]|=0x04):
-	// http://bittorrent.org/beps/bep_0006.html.
-	// Disabled until AllowedFast is implemented. TODO
-	//
-	// DHT ([7]|=1):
-	// http://www.bittorrent.org/beps/bep_0005.html
-	defaultExtensionBytes = "\x00\x00\x00\x00\x00\x10\x00\x01"
-
 	// These are our extended message IDs. Peers will use these values to
 	// select which extension a message is intended for.
 	metadataExtendedId = iota + 1 // 0 is reserved for deleting keys
 	pexExtendedId
 )
+
+func defaultPeerExtensionBytes() peerExtensionBytes {
+	return newPeerExtensionBytes(ExtensionBitDHT, ExtensionBitExtended)
+}
 
 // I could move a lot of these counters to their own file, but I suspect they
 // may be attached to a Client someday.
diff --git a/handshake.go b/handshake.go
index 0262e81c67f033e29169678de8c54dab4c94a2ec..f15f5bbf6377221fd95f22a3b9e08ef1d9027d80 100644
--- a/handshake.go
+++ b/handshake.go
@@ -38,6 +38,13 @@ type (
 	peerExtensionBytes [8]byte
 )
 
+func newPeerExtensionBytes(bits ...ExtensionBit) (ret peerExtensionBytes) {
+	for _, b := range bits {
+		ret.SetBit(b)
+	}
+	return
+}
+
 func (pex peerExtensionBytes) SupportsExtended() bool {
 	return pex.GetBit(ExtensionBitExtended)
 }
diff --git a/handshake_test.go b/handshake_test.go
index b477a2dfda062e53f92ae29d5dcf88cf8a30a702..cc761399bd819fd2f87e5314f3b72ddd507f5f84 100644
--- a/handshake_test.go
+++ b/handshake_test.go
@@ -9,7 +9,7 @@ )
 
 func TestDefaultExtensionBytes(t *testing.T) {
 	var pex peerExtensionBytes
-	missinggo.CopyExact(&pex, defaultExtensionBytes)
+	missinggo.CopyExact(&pex, defaultPeerExtensionBytes())
 	assert.True(t, pex.SupportsDHT())
 	assert.True(t, pex.SupportsExtended())
 	assert.False(t, pex.SupportsFast())