diff --git a/lib/msgstore.go b/lib/msgstore.go
index 77160ae..595908d 100644
--- a/lib/msgstore.go
+++ b/lib/msgstore.go
@@ -55,10 +55,10 @@ func (store *MessageStore) FetchHeaders(uids []uint32,
 
 	// TODO: this could be optimized by pre-allocating toFetch and trimming it
 	// at the end. In practice we expect to get most messages back in one frame.
-	var toFetch imap.SeqSet
+	var toFetch []uint32
 	for _, uid := range uids {
 		if _, ok := store.pendingHeaders[uid]; !ok {
-			toFetch.AddNum(uint32(uid))
+			toFetch = append(toFetch, uid)
 			store.pendingHeaders[uid] = nil
 			if cb != nil {
 				if list, ok := store.headerCallbacks[uid]; ok {
@@ -69,7 +69,7 @@ func (store *MessageStore) FetchHeaders(uids []uint32,
 			}
 		}
 	}
-	if !toFetch.Empty() {
+	if len(toFetch) > 0 {
 		store.worker.PostAction(&types.FetchMessageHeaders{Uids: toFetch}, nil)
 	}
 }
@@ -77,10 +77,10 @@ func (store *MessageStore) FetchHeaders(uids []uint32,
 func (store *MessageStore) FetchFull(uids []uint32, cb func(io.Reader)) {
 	// TODO: this could be optimized by pre-allocating toFetch and trimming it
 	// at the end. In practice we expect to get most messages back in one frame.
-	var toFetch imap.SeqSet
+	var toFetch []uint32
 	for _, uid := range uids {
 		if _, ok := store.pendingBodies[uid]; !ok {
-			toFetch.AddNum(uint32(uid))
+			toFetch = append(toFetch, uid)
 			store.pendingBodies[uid] = nil
 			if cb != nil {
 				if list, ok := store.bodyCallbacks[uid]; ok {
@@ -91,7 +91,7 @@ func (store *MessageStore) FetchFull(uids []uint32, cb func(io.Reader)) {
 			}
 		}
 	}
-	if !toFetch.Empty() {
+	if len(toFetch) > 0 {
 		store.worker.PostAction(&types.FetchFullMessages{Uids: toFetch}, nil)
 	}
 }
@@ -210,24 +210,17 @@ func (store *MessageStore) update() {
 func (store *MessageStore) Delete(uids []uint32,
 	cb func(msg types.WorkerMessage)) {
 
-	var set imap.SeqSet
 	for _, uid := range uids {
-		set.AddNum(uid)
 		store.Deleted[uid] = nil
 	}
 
-	store.worker.PostAction(&types.DeleteMessages{Uids: set}, cb)
+	store.worker.PostAction(&types.DeleteMessages{Uids: uids}, cb)
 	store.update()
 }
 
 func (store *MessageStore) Copy(uids []uint32, dest string, createDest bool,
 	cb func(msg types.WorkerMessage)) {
 
-	var set imap.SeqSet
-	for _, uid := range uids {
-		set.AddNum(uid)
-	}
-
 	if createDest {
 		store.worker.PostAction(&types.CreateDirectory{
 			Directory: dest,
@@ -236,16 +229,14 @@ func (store *MessageStore) Copy(uids []uint32, dest string, createDest bool,
 
 	store.worker.PostAction(&types.CopyMessages{
 		Destination: dest,
-		Uids:        set,
+		Uids:        uids,
 	}, cb)
 }
 
 func (store *MessageStore) Move(uids []uint32, dest string, createDest bool,
 	cb func(msg types.WorkerMessage)) {
 
-	var set imap.SeqSet
 	for _, uid := range uids {
-		set.AddNum(uid)
 		store.Deleted[uid] = nil
 	}
 
@@ -257,13 +248,13 @@ func (store *MessageStore) Move(uids []uint32, dest string, createDest bool,
 
 	store.worker.PostAction(&types.CopyMessages{
 		Destination: dest,
-		Uids:        set,
+		Uids:        uids,
 	}, func(msg types.WorkerMessage) {
 		switch msg.(type) {
 		case *types.Error:
 			cb(msg)
 		case *types.Done:
-			store.worker.PostAction(&types.DeleteMessages{Uids: set}, cb)
+			store.worker.PostAction(&types.DeleteMessages{Uids: uids}, cb)
 		}
 	})
 
@@ -273,14 +264,9 @@ func (store *MessageStore) Move(uids []uint32, dest string, createDest bool,
 func (store *MessageStore) Read(uids []uint32, read bool,
 	cb func(msg types.WorkerMessage)) {
 
-	var set imap.SeqSet
-	for _, uid := range uids {
-		set.AddNum(uid)
-	}
-
 	store.worker.PostAction(&types.ReadMessages{
 		Read: read,
-		Uids: set,
+		Uids: uids,
 	}, cb)
 }
 
diff --git a/worker/imap/fetch.go b/worker/imap/fetch.go
index d5bb9aa..fe25977 100644
--- a/worker/imap/fetch.go
+++ b/worker/imap/fetch.go
@@ -31,8 +31,7 @@ func (imapw *IMAPWorker) handleFetchMessageHeaders(
 		imap.FetchUid,
 		section.FetchItem(),
 	}
-
-	imapw.handleFetchMessages(msg, &msg.Uids, items, section)
+	imapw.handleFetchMessages(msg, msg.Uids, items, section)
 }
 
 func (imapw *IMAPWorker) handleFetchMessageBodyPart(
@@ -46,9 +45,7 @@ func (imapw *IMAPWorker) handleFetchMessageBodyPart(
 		imap.FetchUid,
 		section.FetchItem(),
 	}
-	uids := imap.SeqSet{}
-	uids.AddNum(msg.Uid)
-	imapw.handleFetchMessages(msg, &uids, items, section)
+	imapw.handleFetchMessages(msg, []uint32{msg.Uid}, items, section)
 }
 
 func (imapw *IMAPWorker) handleFetchFullMessages(
@@ -61,11 +58,11 @@ func (imapw *IMAPWorker) handleFetchFullMessages(
 		imap.FetchUid,
 		section.FetchItem(),
 	}
-	imapw.handleFetchMessages(msg, &msg.Uids, items, section)
+	imapw.handleFetchMessages(msg, msg.Uids, items, section)
 }
 
 func (imapw *IMAPWorker) handleFetchMessages(
-	msg types.WorkerMessage, uids *imap.SeqSet, items []imap.FetchItem,
+	msg types.WorkerMessage, uids []uint32, items []imap.FetchItem,
 	section *imap.BodySectionName) {
 
 	messages := make(chan *imap.Message)
@@ -132,7 +129,8 @@ func (imapw *IMAPWorker) handleFetchMessages(
 		done <- nil
 	}()
 
-	if err := imapw.client.UidFetch(uids, items, messages); err != nil {
+	set := toSeqSet(uids)
+	if err := imapw.client.UidFetch(set, items, messages); err != nil {
 		imapw.worker.PostMessage(&types.Error{
 			Message: types.RespondTo(msg),
 			Error:   err,
diff --git a/worker/imap/flags.go b/worker/imap/flags.go
index 0122d8e..57211a6 100644
--- a/worker/imap/flags.go
+++ b/worker/imap/flags.go
@@ -9,7 +9,8 @@ import (
 func (imapw *IMAPWorker) handleDeleteMessages(msg *types.DeleteMessages) {
 	item := imap.FormatFlagsOp(imap.AddFlags, true)
 	flags := []interface{}{imap.DeletedFlag}
-	if err := imapw.client.UidStore(&msg.Uids, item, flags, nil); err != nil {
+	uids := toSeqSet(msg.Uids)
+	if err := imapw.client.UidStore(uids, item, flags, nil); err != nil {
 		imapw.worker.PostMessage(&types.Error{
 			Message: types.RespondTo(msg),
 			Error:   err,
@@ -49,7 +50,8 @@ func (imapw *IMAPWorker) handleReadMessages(msg *types.ReadMessages) {
 		item = imap.FormatFlagsOp(imap.RemoveFlags, true)
 		flags = []interface{}{imap.SeenFlag}
 	}
-	if err := imapw.client.UidStore(&msg.Uids, item, flags, nil); err != nil {
+	uids := toSeqSet(msg.Uids)
+	if err := imapw.client.UidStore(uids, item, flags, nil); err != nil {
 		imapw.worker.PostMessage(&types.Error{
 			Message: types.RespondTo(msg),
 			Error:   err,
diff --git a/worker/imap/imap.go b/worker/imap/imap.go
new file mode 100644
index 0000000..28bac93
--- /dev/null
+++ b/worker/imap/imap.go
@@ -0,0 +1,13 @@
+package imap
+
+import (
+	"github.com/emersion/go-imap"
+)
+
+func toSeqSet(uids []uint32) *imap.SeqSet {
+	var set imap.SeqSet
+	for _, uid := range uids {
+		set.AddNum(uid)
+	}
+	return &set
+}
diff --git a/worker/imap/movecopy.go b/worker/imap/movecopy.go
index 6cf3fe1..b01dab7 100644
--- a/worker/imap/movecopy.go
+++ b/worker/imap/movecopy.go
@@ -7,7 +7,8 @@ import (
 )
 
 func (imapw *IMAPWorker) handleCopyMessages(msg *types.CopyMessages) {
-	if err := imapw.client.UidCopy(&msg.Uids, msg.Destination); err != nil {
+	uids := toSeqSet(msg.Uids)
+	if err := imapw.client.UidCopy(uids, msg.Destination); err != nil {
 		imapw.worker.PostMessage(&types.Error{
 			Message: types.RespondTo(msg),
 			Error:   err,
diff --git a/worker/types/messages.go b/worker/types/messages.go
index bb2505a..bab14e0 100644
--- a/worker/types/messages.go
+++ b/worker/types/messages.go
@@ -94,12 +94,12 @@ type CreateDirectory struct {
 
 type FetchMessageHeaders struct {
 	Message
-	Uids imap.SeqSet
+	Uids []uint32
 }
 
 type FetchFullMessages struct {
 	Message
-	Uids imap.SeqSet
+	Uids []uint32
 }
 
 type FetchMessageBodyPart struct {
@@ -110,20 +110,20 @@ type FetchMessageBodyPart struct {
 
 type DeleteMessages struct {
 	Message
-	Uids imap.SeqSet
+	Uids []uint32
 }
 
 // Marks messages as read or unread
 type ReadMessages struct {
 	Message
 	Read bool
-	Uids imap.SeqSet
+	Uids []uint32
 }
 
 type CopyMessages struct {
 	Message
 	Destination string
-	Uids        imap.SeqSet
+	Uids        []uint32
 }
 
 type AppendMessage struct {