diff --git a/.github/workflows/check.yml b/.github/workflows/check.yml
index 10dc835..b6cb7ff 100644
--- a/.github/workflows/check.yml
+++ b/.github/workflows/check.yml
@@ -9,15 +9,15 @@ jobs:
       - name: Get sources
         uses: actions/checkout@v3
 
-      - name: Set up Go 1.18
+      - name: Set up Go 1.21
         uses: actions/setup-go@v3
         with:
-          go-version: '1.18'
+          go-version: '1.21'
 
       - name: Run golangci-lint
         uses: golangci/golangci-lint-action@v3
         with:
-          version: v1.50.0
+          version: v1.55.2
           args: --timeout=180s
           skip-cache: true
 
diff --git a/keyring.go b/keyring.go
index 2037b11..7aecf98 100644
--- a/keyring.go
+++ b/keyring.go
@@ -12,6 +12,7 @@ import (
 	"github.com/ProtonMail/go-crypto/openpgp/armor"
 	"github.com/ProtonMail/gopenpgp/v2/crypto"
 	"github.com/bradenaw/juniper/xslices"
+	"golang.org/x/exp/slices"
 )
 
 func ExtractSignatures(kr *crypto.KeyRing, arm string) ([]Signature, error) {
@@ -148,7 +149,7 @@ func (keys Keys) Unlock(passphrase []byte, userKR *crypto.KeyRing) (*crypto.KeyR
 		return nil, err
 	}
 
-	for _, key := range xslices.Filter(keys, func(key Key) bool { return bool(key.Active) }) {
+	for _, key := range slices.DeleteFunc(slices.Clone(keys), func(key Key) bool { return !bool(key.Active) }) {
 		unlocked, err := key.Unlock(passphrase, userKR)
 		if err != nil {
 			log.WithField("KeyID", key.ID).WithError(err).Warning("Cannot unlock key")
diff --git a/message_import.go b/message_import.go
index f0d8321..3cd9f24 100644
--- a/message_import.go
+++ b/message_import.go
@@ -13,6 +13,7 @@ import (
 	"github.com/bradenaw/juniper/stream"
 	"github.com/bradenaw/juniper/xslices"
 	"github.com/go-resty/resty/v2"
+	"golang.org/x/exp/slices"
 )
 
 const (
@@ -38,7 +39,7 @@ func (c *Client) ImportMessages(ctx context.Context, addrKR *crypto.KeyRing, wor
 	}
 
 	// If any of the messages exceed the maximum import size, return an error.
-	if xslices.Any(req, func(req ImportReq) bool { return len(req.Message) > maxImportSize }) {
+	if slices.ContainsFunc(req, func(req ImportReq) bool { return len(req.Message) > maxImportSize }) {
 		return nil, ErrImportSizeExceeded
 	}
 
diff --git a/salt_types.go b/salt_types.go
index 8f06861..b2120ce 100644
--- a/salt_types.go
+++ b/salt_types.go
@@ -5,7 +5,7 @@ import (
 	"fmt"
 
 	"github.com/ProtonMail/go-srp"
-	"github.com/bradenaw/juniper/xslices"
+	"golang.org/x/exp/slices"
 )
 
 type Salt struct {
@@ -15,7 +15,7 @@ type Salt struct {
 type Salts []Salt
 
 func (salts Salts) SaltForKey(keyPass []byte, keyID string) ([]byte, error) {
-	idx := xslices.IndexFunc(salts, func(salt Salt) bool {
+	idx := slices.IndexFunc(salts, func(salt Salt) bool {
 		return salt.ID == keyID
 	})
 
diff --git a/server/backend/api.go b/server/backend/api.go
index 6fc3731..f9e1181 100644
--- a/server/backend/api.go
+++ b/server/backend/api.go
@@ -341,8 +341,8 @@ func (b *Backend) GetLabels(userID string, types ...proton.LabelType) ([]proton.
 				}
 
 				if len(types) > 0 {
-					res = xslices.Filter(res, func(label proton.Label) bool {
-						return slices.Contains(types, label.Type)
+					res = slices.DeleteFunc(res, func(label proton.Label) bool {
+						return !slices.Contains(types, label.Type)
 					})
 				}
 
@@ -431,7 +431,7 @@ func (b *Backend) DeleteLabel(userID, labelID string) error {
 						return err
 					}
 
-					acc.labelIDs = xslices.Filter(acc.labelIDs, func(otherID string) bool { return otherID != labelID })
+					acc.labelIDs = slices.DeleteFunc(acc.labelIDs, func(otherID string) bool { return otherID == labelID })
 					acc.updateIDs = append(acc.updateIDs, updateID)
 				}
 
@@ -500,7 +500,7 @@ func (b *Backend) GetMessages(userID string, page, pageSize int, filter proton.M
 				// deleted in between this metadata request. The backend has the information stored differently and can
 				// resolve these gaps.
 				if filter.EndID != "" {
-					index := xslices.IndexFunc(metadata, func(metadata proton.MessageMetadata) bool {
+					index := slices.IndexFunc(metadata, func(metadata proton.MessageMetadata) bool {
 						return metadata.ID == filter.EndID
 					})
 
@@ -509,38 +509,38 @@ func (b *Backend) GetMessages(userID string, page, pageSize int, filter proton.M
 					}
 				}
 
-				metadata = xslices.Filter(metadata, func(metadata proton.MessageMetadata) bool {
+				metadata = slices.DeleteFunc(metadata, func(metadata proton.MessageMetadata) bool {
 					if len(filter.ID) > 0 {
 						if !slices.Contains(filter.ID, metadata.ID) {
-							return false
+							return true
 						}
 					}
 
 					if filter.Subject != "" {
 						if !strings.Contains(metadata.Subject, filter.Subject) {
-							return false
+							return true
 						}
 					}
 
 					if filter.AddressID != "" {
 						if filter.AddressID != metadata.AddressID {
-							return false
+							return true
 						}
 					}
 
 					if filter.ExternalID != "" {
 						if filter.ExternalID != metadata.ExternalID {
-							return false
+							return true
 						}
 					}
 
 					if filter.LabelID != "" {
 						if !slices.Contains(metadata.LabelIDs, filter.LabelID) {
-							return false
+							return true
 						}
 					}
 
-					return true
+					return false
 				})
 
 				pages := xslices.Chunk(metadata, pageSize)
@@ -712,7 +712,7 @@ func (b *Backend) DeleteMessage(userID, messageID string) error {
 					return err
 				}
 
-				acc.messageIDs = xslices.Filter(acc.messageIDs, func(otherID string) bool { return otherID != messageID })
+				acc.messageIDs = slices.DeleteFunc(acc.messageIDs, func(otherID string) bool { return otherID == messageID })
 				acc.updateIDs = append(acc.updateIDs, updateID)
 
 				return nil
@@ -1045,7 +1045,7 @@ func (b *Backend) GetEvent(userID, rawEventID string) (event proton.Event, more
 			return withMessages(b, func(messages map[string]*message) (proton.Event, error) {
 				return withLabels(b, func(labels map[string]*label) (proton.Event, error) {
 					return withAtts(b, func(attachments map[string]*attachment) (proton.Event, error) {
-						firstUpdate := xslices.Index(acc.updateIDs, eventID) + 1
+						firstUpdate := slices.Index(acc.updateIDs, eventID) + 1
 						lastUpdate := getLastUpdateIndex(len(acc.updateIDs), firstUpdate, b.maxUpdatesPerEvent)
 
 						updates, err := withUpdates(b, func(updates map[ID]update) ([]update, error) {
diff --git a/server/backend/backend.go b/server/backend/backend.go
index 408242d..c8da539 100644
--- a/server/backend/backend.go
+++ b/server/backend/backend.go
@@ -235,7 +235,7 @@ func (b *Backend) RemoveUserKey(userID, keyID string) error {
 			return fmt.Errorf("user %s does not exist", userID)
 		}
 
-		idx := xslices.IndexFunc(user.keys, func(key key) bool {
+		idx := slices.IndexFunc(user.keys, func(key key) bool {
 			return key.keyID == keyID
 		})
 
@@ -463,7 +463,7 @@ func (b *Backend) RemoveAddress(userID, addrID string) error {
 func (b *Backend) RemoveAddressKey(userID, addrID, keyID string) error {
 	return writeBackendRet(b, func(b *unsafeBackend) error {
 		return b.withAcc(userID, func(acc *account) error {
-			idx := xslices.IndexFunc(acc.addresses[addrID].keys, func(key key) bool {
+			idx := slices.IndexFunc(acc.addresses[addrID].keys, func(key key) bool {
 				return key.keyID == keyID
 			})
 
diff --git a/server/backend/message.go b/server/backend/message.go
index 59c5873..0e67768 100644
--- a/server/backend/message.go
+++ b/server/backend/message.go
@@ -320,16 +320,16 @@ func (msg *message) addLabel(labelID string, labels map[string]*label) {
 }
 
 func (msg *message) addFlagLabel(labelID string, labels map[string]*label) {
-	msg.labelIDs = xslices.Filter(msg.labelIDs, func(otherLabelID string) bool {
-		return labels[otherLabelID].labelType == proton.LabelTypeLabel
+	msg.labelIDs = slices.DeleteFunc(msg.labelIDs, func(otherLabelID string) bool {
+		return labels[otherLabelID].labelType != proton.LabelTypeLabel
 	})
 
 	msg.sysLabel = nil
 }
 
 func (msg *message) addSystemLabel(labelID string, labels map[string]*label) {
-	msg.labelIDs = xslices.Filter(msg.labelIDs, func(otherLabelID string) bool {
-		return labels[otherLabelID].labelType == proton.LabelTypeLabel
+	msg.labelIDs = slices.DeleteFunc(msg.labelIDs, func(otherLabelID string) bool {
+		return labels[otherLabelID].labelType != proton.LabelTypeLabel
 	})
 
 	msg.sysLabel = &labelID
@@ -337,8 +337,8 @@ func (msg *message) addSystemLabel(labelID string, labels map[string]*label) {
 
 func (msg *message) addUserLabel(label *label, labels map[string]*label) {
 	if label.labelType != proton.LabelTypeLabel {
-		msg.labelIDs = xslices.Filter(msg.labelIDs, func(otherLabelID string) bool {
-			return labels[otherLabelID].labelType == proton.LabelTypeLabel
+		msg.labelIDs = slices.DeleteFunc(msg.labelIDs, func(otherLabelID string) bool {
+			return labels[otherLabelID].labelType != proton.LabelTypeLabel
 		})
 
 		msg.sysLabel = pointer("")
@@ -380,8 +380,8 @@ func (msg *message) remSystemLabel(labelID string, labels map[string]*label) {
 }
 
 func (msg *message) remUserLabel(label *label, labels map[string]*label) {
-	msg.labelIDs = xslices.Filter(msg.labelIDs, func(otherLabelID string) bool {
-		return otherLabelID != label.labelID
+	msg.labelIDs = slices.DeleteFunc(msg.labelIDs, func(otherLabelID string) bool {
+		return otherLabelID == label.labelID
 	})
 }
 
diff --git a/server/backend/updates.go b/server/backend/updates.go
index 75544af..83d2b68 100644
--- a/server/backend/updates.go
+++ b/server/backend/updates.go
@@ -1,8 +1,9 @@
 package backend
 
 import (
+	"slices"
+
 	"github.com/ProtonMail/go-proton-api"
-	"github.com/bradenaw/juniper/xslices"
 )
 
 func merge(updates []update) []update {
@@ -10,7 +11,7 @@ func merge(updates []update) []update {
 		return updates
 	}
 
-	if merged := merge(updates[1:]); xslices.IndexFunc(merged, func(other update) bool {
+	if merged := merge(updates[1:]); slices.IndexFunc(merged, func(other update) bool {
 		return other.replaces(updates[0])
 	}) < 0 {
 		return append([]update{updates[0]}, merged...)
diff --git a/server/server_test.go b/server/server_test.go
index a3c0bef..23c7c75 100644
--- a/server/server_test.go
+++ b/server/server_test.go
@@ -2218,12 +2218,12 @@ func TestServer_GetMessageGroupCount(t *testing.T) {
 			counts, err := c.GetGroupedMessageCount(ctx)
 			require.NoError(t, err)
 
-			counts = xslices.Filter(counts, func(t proton.MessageGroupCount) bool {
+			counts = slices.DeleteFunc(counts, func(t proton.MessageGroupCount) bool {
 				switch t.LabelID {
 				case proton.InboxLabel, proton.TrashLabel, proton.ArchiveLabel, proton.AllMailLabel, proton.SentLabel:
-					return true
-				default:
 					return false
+				default:
+					return true
 				}
 			})
 			require.NotEmpty(t, counts)
@@ -2377,7 +2377,7 @@ func TestServer_Contacts(t *testing.T) {
 			require.Len(t, contacts, len(testContacts))
 
 			for _, v := range testContacts {
-				require.NotEqual(t, -1, xslices.IndexFunc(contacts, func(contact proton.Contact) bool {
+				require.NotEqual(t, -1, slices.IndexFunc(contacts, func(contact proton.Contact) bool {
 					return contact.Name == v.Name
 				}))
 			}