diff --git a/vfs/vfscache/item.go b/vfs/vfscache/item.go
index 702847719..b76688db1 100644
--- a/vfs/vfscache/item.go
+++ b/vfs/vfscache/item.go
@@ -737,7 +737,7 @@ func (item *Item) Close(storeFn StoreFn) (err error) {
 			item.c.writeback.SetID(&item.writeBackID)
 			id := item.writeBackID
 			item.mu.Unlock()
-			item.c.writeback.Add(id, item.name, item.modified, func(ctx context.Context) error {
+			item.c.writeback.Add(id, item.name, item.info.Size, item.modified, func(ctx context.Context) error {
 				return item.store(ctx, storeFn)
 			})
 			item.mu.Lock()
diff --git a/vfs/vfscache/writeback/writeback.go b/vfs/vfscache/writeback/writeback.go
index 9801a2d3c..33c5616c2 100644
--- a/vfs/vfscache/writeback/writeback.go
+++ b/vfs/vfscache/writeback/writeback.go
@@ -62,6 +62,7 @@ func New(ctx context.Context, opt *vfscommon.Options) *WriteBack {
 // writeBack.mu must be held to manipulate this
 type writeBackItem struct {
 	name      string             // name of the item so we don't have to read it from item
+	size      int64              // size of the item so we don't have to read it from item
 	id        Handle             // id of the item
 	index     int                // index into the priority queue for update
 	expiry    time.Time          // When this expires we will write it back
@@ -135,10 +136,11 @@ func (wb *WriteBack) _newExpiry() time.Time {
 // make a new writeBackItem
 //
 // call with the lock held
-func (wb *WriteBack) _newItem(id Handle, name string) *writeBackItem {
+func (wb *WriteBack) _newItem(id Handle, name string, size int64) *writeBackItem {
 	wb.SetID(&id)
 	wbItem := &writeBackItem{
 		name:   name,
+		size:   size,
 		expiry: wb._newExpiry(),
 		delay:  time.Duration(wb.opt.WriteBack),
 		id:     id,
@@ -256,13 +258,13 @@ func (wb *WriteBack) SetID(pid *Handle) {
 //
 // If modified is false then it it doesn't cancel a pending upload if
 // there is one as there is no need.
-func (wb *WriteBack) Add(id Handle, name string, modified bool, putFn PutFn) Handle {
+func (wb *WriteBack) Add(id Handle, name string, size int64, modified bool, putFn PutFn) Handle {
 	wb.mu.Lock()
 	defer wb.mu.Unlock()
 
 	wbItem, ok := wb.lookup[id]
 	if !ok {
-		wbItem = wb._newItem(id, name)
+		wbItem = wb._newItem(id, name, size)
 	} else {
 		if wbItem.uploading && modified {
 			// We are uploading already so cancel the upload
@@ -272,6 +274,7 @@ func (wb *WriteBack) Add(id Handle, name string, modified bool, putFn PutFn) Han
 		wb.items._update(wbItem, wb._newExpiry())
 	}
 	wbItem.putFn = putFn
+	wbItem.size = size
 	wb._resetTimer()
 	return wbItem.id
 }
diff --git a/vfs/vfscache/writeback/writeback_test.go b/vfs/vfscache/writeback/writeback_test.go
index 64645eccf..21d8bae7e 100644
--- a/vfs/vfscache/writeback/writeback_test.go
+++ b/vfs/vfscache/writeback/writeback_test.go
@@ -122,15 +122,15 @@ func TestWriteBackItemCRUD(t *testing.T) {
 	// _peekItem empty
 	assert.Nil(t, wb._peekItem())
 
-	wbItem1 := wb._newItem(0, "one")
+	wbItem1 := wb._newItem(0, "one", 10)
 	checkOnHeap(t, wb, wbItem1)
 	checkInLookup(t, wb, wbItem1)
 
-	wbItem2 := wb._newItem(0, "two")
+	wbItem2 := wb._newItem(0, "two", 10)
 	checkOnHeap(t, wb, wbItem2)
 	checkInLookup(t, wb, wbItem2)
 
-	wbItem3 := wb._newItem(0, "three")
+	wbItem3 := wb._newItem(0, "three", 10)
 	checkOnHeap(t, wb, wbItem3)
 	checkInLookup(t, wb, wbItem3)
 
@@ -201,7 +201,7 @@ func TestWriteBackResetTimer(t *testing.T) {
 	// Check timer is stopped
 	assertTimerRunning(t, wb, false)
 
-	_ = wb._newItem(0, "three")
+	_ = wb._newItem(0, "three", 10)
 
 	// Reset the timer on an queue with stuff
 	wb._resetTimer()
@@ -297,7 +297,7 @@ func TestWriteBackAddOK(t *testing.T) {
 	wb.SetID(&inID)
 	assert.Equal(t, Handle(1), inID)
 
-	id := wb.Add(inID, "one", true, pi.put)
+	id := wb.Add(inID, "one", 10, true, pi.put)
 	assert.Equal(t, inID, id)
 	wbItem := wb.lookup[id]
 	checkOnHeap(t, wb, wbItem)
@@ -321,7 +321,7 @@ func TestWriteBackAddFailRetry(t *testing.T) {
 
 	pi := newPutItem(t)
 
-	id := wb.Add(0, "one", true, pi.put)
+	id := wb.Add(0, "one", 10, true, pi.put)
 	wbItem := wb.lookup[id]
 	checkOnHeap(t, wb, wbItem)
 	checkInLookup(t, wb, wbItem)
@@ -354,8 +354,9 @@ func TestWriteBackAddUpdate(t *testing.T) {
 
 	pi := newPutItem(t)
 
-	id := wb.Add(0, "one", true, pi.put)
+	id := wb.Add(0, "one", 10, true, pi.put)
 	wbItem := wb.lookup[id]
+	assert.Equal(t, int64(10), wbItem.size) // check size
 	checkOnHeap(t, wb, wbItem)
 	checkInLookup(t, wb, wbItem)
 	assert.Equal(t, "one", wb.string(t))
@@ -367,9 +368,10 @@ func TestWriteBackAddUpdate(t *testing.T) {
 	// Now the upload has started add another one
 
 	pi2 := newPutItem(t)
-	id2 := wb.Add(id, "one", true, pi2.put)
+	id2 := wb.Add(id, "one", 20, true, pi2.put)
 	assert.Equal(t, id, id2)
-	checkOnHeap(t, wb, wbItem) // object awaiting writeback time
+	assert.Equal(t, int64(20), wbItem.size) // check size has changed
+	checkOnHeap(t, wb, wbItem)              // object awaiting writeback time
 	checkInLookup(t, wb, wbItem)
 
 	// check the previous transfer was cancelled
@@ -393,7 +395,7 @@ func TestWriteBackAddUpdateNotModified(t *testing.T) {
 
 	pi := newPutItem(t)
 
-	id := wb.Add(0, "one", false, pi.put)
+	id := wb.Add(0, "one", 10, false, pi.put)
 	wbItem := wb.lookup[id]
 	checkOnHeap(t, wb, wbItem)
 	checkInLookup(t, wb, wbItem)
@@ -406,7 +408,7 @@ func TestWriteBackAddUpdateNotModified(t *testing.T) {
 	// Now the upload has started add another one
 
 	pi2 := newPutItem(t)
-	id2 := wb.Add(id, "one", false, pi2.put)
+	id2 := wb.Add(id, "one", 10, false, pi2.put)
 	assert.Equal(t, id, id2)
 	checkNotOnHeap(t, wb, wbItem) // object still being transferred
 	checkInLookup(t, wb, wbItem)
@@ -432,7 +434,7 @@ func TestWriteBackAddUpdateNotStarted(t *testing.T) {
 
 	pi := newPutItem(t)
 
-	id := wb.Add(0, "one", true, pi.put)
+	id := wb.Add(0, "one", 10, true, pi.put)
 	wbItem := wb.lookup[id]
 	checkOnHeap(t, wb, wbItem)
 	checkInLookup(t, wb, wbItem)
@@ -441,7 +443,7 @@ func TestWriteBackAddUpdateNotStarted(t *testing.T) {
 	// Immediately add another upload before the first has started
 
 	pi2 := newPutItem(t)
-	id2 := wb.Add(id, "one", true, pi2.put)
+	id2 := wb.Add(id, "one", 10, true, pi2.put)
 	assert.Equal(t, id, id2)
 	checkOnHeap(t, wb, wbItem) // object still awaiting transfer
 	checkInLookup(t, wb, wbItem)
@@ -470,7 +472,7 @@ func TestWriteBackGetStats(t *testing.T) {
 
 	pi := newPutItem(t)
 
-	wb.Add(0, "one", true, pi.put)
+	wb.Add(0, "one", 10, true, pi.put)
 
 	inProgress, queued := wb.Stats()
 	assert.Equal(t, queued, 1)
@@ -506,7 +508,7 @@ func TestWriteBackMaxQueue(t *testing.T) {
 	for i := 0; i < toTransfer; i++ {
 		pi := newPutItem(t)
 		pis = append(pis, pi)
-		wb.Add(0, fmt.Sprintf("number%d", 1), true, pi.put)
+		wb.Add(0, fmt.Sprintf("number%d", 1), 10, true, pi.put)
 	}
 
 	inProgress, queued := wb.Stats()
@@ -551,7 +553,7 @@ func TestWriteBackRename(t *testing.T) {
 
 	// add item
 	pi1 := newPutItem(t)
-	id := wb.Add(0, "one", true, pi1.put)
+	id := wb.Add(0, "one", 10, true, pi1.put)
 	wbItem := wb.lookup[id]
 	checkOnHeap(t, wb, wbItem)
 	checkInLookup(t, wb, wbItem)
@@ -566,7 +568,7 @@ func TestWriteBackRename(t *testing.T) {
 
 	// add item
 	pi2 := newPutItem(t)
-	id = wb.Add(id, "two", true, pi2.put)
+	id = wb.Add(id, "two", 10, true, pi2.put)
 	wbItem = wb.lookup[id]
 	checkOnHeap(t, wb, wbItem)
 	checkInLookup(t, wb, wbItem)
@@ -591,9 +593,9 @@ func TestWriteBackRenameDuplicates(t *testing.T) {
 	wb, cancel := newTestWriteBack(t)
 	defer cancel()
 
-	// add item "one"
+	// add item "one", 10
 	pi1 := newPutItem(t)
-	id1 := wb.Add(0, "one", true, pi1.put)
+	id1 := wb.Add(0, "one", 10, true, pi1.put)
 	wbItem1 := wb.lookup[id1]
 	checkOnHeap(t, wb, wbItem1)
 	checkInLookup(t, wb, wbItem1)
@@ -605,7 +607,7 @@ func TestWriteBackRenameDuplicates(t *testing.T) {
 
 	// add item "two"
 	pi2 := newPutItem(t)
-	id2 := wb.Add(0, "two", true, pi2.put)
+	id2 := wb.Add(0, "two", 10, true, pi2.put)
 	wbItem2 := wb.lookup[id2]
 	checkOnHeap(t, wb, wbItem2)
 	checkInLookup(t, wb, wbItem2)
@@ -641,7 +643,7 @@ func TestWriteBackCancelUpload(t *testing.T) {
 
 	// add item
 	pi := newPutItem(t)
-	id := wb.Add(0, "one", true, pi.put)
+	id := wb.Add(0, "one", 10, true, pi.put)
 	wbItem := wb.lookup[id]
 	checkOnHeap(t, wb, wbItem)
 	checkInLookup(t, wb, wbItem)