diff --git a/pkg/blobserver/blobhub.go b/pkg/blobserver/blobhub.go
index 40837b9e3..99a143f2c 100644
--- a/pkg/blobserver/blobhub.go
+++ b/pkg/blobserver/blobhub.go
@@ -33,13 +33,13 @@ type BlobHub interface {
 	//
 	// If any synchronous receive hooks are registered, they're run before
 	// NotifyBlobReceived returns and their error is returned.
-	NotifyBlobReceived(blob blob.Ref) error
+	NotifyBlobReceived(blob.SizedRef) error
 
 	// AddReceiveHook adds a hook that is synchronously run
 	// whenever blobs are received.  All registered hooks are run
 	// on each blob upload but if more than one returns an error,
 	// NotifyBlobReceived will only return one of the errors.
-	AddReceiveHook(func(blob.Ref) error)
+	AddReceiveHook(func(blob.SizedRef) error)
 
 	RegisterListener(ch chan<- blob.Ref)
 	UnregisterListener(ch chan<- blob.Ref)
@@ -107,15 +107,17 @@ func WaitForBlob(storage interface{}, deadline time.Time, blobs []blob.Ref) {
 type memHub struct {
 	mu sync.RWMutex
 
-	hooks         []func(blob.Ref) error
+	hooks         []func(blob.SizedRef) error
 	listeners     map[chan<- blob.Ref]bool
 	blobListeners map[blob.Ref]map[chan<- blob.Ref]bool
 }
 
-func (h *memHub) NotifyBlobReceived(br blob.Ref) error {
+func (h *memHub) NotifyBlobReceived(sb blob.SizedRef) error {
 	h.mu.RLock()
 	defer h.mu.RUnlock()
 
+	br := sb.Ref
+
 	// Callback channels to notify, nil until non-empty
 	var notify []chan<- blob.Ref
 
@@ -145,7 +147,7 @@ func (h *memHub) NotifyBlobReceived(br blob.Ref) error {
 
 	var ret error
 	for _, hook := range h.hooks {
-		if err := hook(br); err != nil && ret == nil {
+		if err := hook(sb); err != nil && ret == nil {
 			ret = err
 		}
 	}
@@ -200,7 +202,7 @@ func (h *memHub) UnregisterBlobListener(br blob.Ref, ch chan<- blob.Ref) {
 	}
 }
 
-func (h *memHub) AddReceiveHook(hook func(blob.Ref) error) {
+func (h *memHub) AddReceiveHook(hook func(blob.SizedRef) error) {
 	h.mu.Lock()
 	defer h.mu.Unlock()
 	h.hooks = append(h.hooks, hook)
diff --git a/pkg/blobserver/blobhub_test.go b/pkg/blobserver/blobhub_test.go
index 324c6c159..088e04487 100644
--- a/pkg/blobserver/blobhub_test.go
+++ b/pkg/blobserver/blobhub_test.go
@@ -17,10 +17,11 @@ limitations under the License.
 package blobserver
 
 import (
-	"camlistore.org/pkg/blob"
-	. "camlistore.org/pkg/test/asserts"
 	"testing"
 	"time"
+
+	"camlistore.org/pkg/blob"
+	. "camlistore.org/pkg/test/asserts"
 )
 
 func TestHubRegistration(t *testing.T) {
@@ -72,14 +73,14 @@ func TestHubFiring(t *testing.T) {
 	blob1 := blob.MustParse("sha1-0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33")
 	blobsame := blob.MustParse("sha1-0beec7b5ea3f0fdbc95d0dd47f3c5bc275da8a33")
 
-	hub.NotifyBlobReceived(blob1) // no-op
+	hub.NotifyBlobReceived(blob.SizedRef{blob1, 123}) // no-op
 
 	hub.RegisterListener(ch)
 	hub.RegisterBlobListener(blob1, bch)
 
-	hub.NotifyBlobReceived(blobsame)
+	hub.NotifyBlobReceived(blob.SizedRef{blobsame, 456})
 
-	tmr1 := time.NewTimer(1e9)
+	tmr1 := time.NewTimer(1 * time.Second)
 	select {
 	case <-tmr1.C:
 		t.Fatal("timer expired on receiving from ch")
diff --git a/pkg/blobserver/receive.go b/pkg/blobserver/receive.go
index 48d3d6622..820702aa4 100644
--- a/pkg/blobserver/receive.go
+++ b/pkg/blobserver/receive.go
@@ -50,7 +50,7 @@ func receive(dst BlobReceiver, br blob.Ref, src io.Reader, checkHash bool) (sb b
 	if err != nil {
 		return
 	}
-	err = GetHub(dst).NotifyBlobReceived(sb.Ref)
+	err = GetHub(dst).NotifyBlobReceived(sb)
 	return
 }
 
diff --git a/pkg/server/sync.go b/pkg/server/sync.go
index 9a086cc57..883a4416a 100644
--- a/pkg/server/sync.go
+++ b/pkg/server/sync.go
@@ -142,6 +142,7 @@ func newSyncFromConfig(ld blobserver.Loader, conf jsonconfig.Obj) (http.Handler,
 		go synch.syncQueueLoop()
 	}
 
+	blobserver.GetHub(fromBs).AddReceiveHook(synch.enqueue)
 	return synch, nil
 }
 
@@ -472,12 +473,21 @@ func (sh *SyncHandler) ReceiveBlob(br blob.Ref, r io.Reader) (sb blob.SizedRef,
 	if err != nil {
 		return
 	}
+	sb = blob.SizedRef{br, n}
+	return sb, sh.enqueue(sb)
+}
+
+func (sh *SyncHandler) enqueue(sb blob.SizedRef) error {
 	// TODO: include current time in encoded value, to attempt to
 	// do in-order delivery to remote side later? Possible
 	// friendly optimization later. Might help peer's indexer have
 	// less missing deps.
-	err = sh.queue.Set(br.String(), fmt.Sprint(n))
-	return blob.SizedRef{br, n}, err
+	if err := sh.queue.Set(sb.Ref.String(), fmt.Sprint(sb.Size)); err != nil {
+		return err
+	}
+	// TODO(bradfitz): non-blocking send to wake up looping
+	// goroutine if it's sleeping.
+	return nil
 }
 
 // TODO(bradfitz): implement these? what do they mean? possibilities: