diff --git a/lib/db/leveldb.go b/lib/db/leveldb.go
index f3b74bab1..896e3ee04 100644
--- a/lib/db/leveldb.go
+++ b/lib/db/leveldb.go
@@ -89,78 +89,8 @@ type dbReader interface {
 // Flush batches to disk when they contain this many records.
 const batchFlushSize = 64
 
-// deviceKey returns a byte slice encoding the following information:
-//	   keyTypeDevice (1 byte)
-//	   folder (64 bytes)
-//	   device (32 bytes)
-//	   name (variable size)
-func deviceKey(folder, device, file []byte) []byte {
-	return deviceKeyInto(nil, folder, device, file)
-}
-
-func deviceKeyInto(k []byte, folder, device, file []byte) []byte {
-	reqLen := 1 + 64 + 32 + len(file)
-	if len(k) < reqLen {
-		k = make([]byte, reqLen)
-	}
-	k[0] = KeyTypeDevice
-	if len(folder) > 64 {
-		panic("folder name too long")
-	}
-	copy(k[1:], []byte(folder))
-	copy(k[1+64:], device[:])
-	copy(k[1+64+32:], []byte(file))
-	return k[:reqLen]
-}
-
-func deviceKeyName(key []byte) []byte {
-	return key[1+64+32:]
-}
-
-func deviceKeyFolder(key []byte) []byte {
-	folder := key[1 : 1+64]
-	izero := bytes.IndexByte(folder, 0)
-	if izero < 0 {
-		return folder
-	}
-	return folder[:izero]
-}
-
-func deviceKeyDevice(key []byte) []byte {
-	return key[1+64 : 1+64+32]
-}
-
-// globalKey returns a byte slice encoding the following information:
-//	   keyTypeGlobal (1 byte)
-//	   folder (64 bytes)
-//	   name (variable size)
-func globalKey(folder, file []byte) []byte {
-	k := make([]byte, 1+64+len(file))
-	k[0] = KeyTypeGlobal
-	if len(folder) > 64 {
-		panic("folder name too long")
-	}
-	copy(k[1:], []byte(folder))
-	copy(k[1+64:], []byte(file))
-	return k
-}
-
-func globalKeyName(key []byte) []byte {
-	return key[1+64:]
-}
-
-func globalKeyFolder(key []byte) []byte {
-	folder := key[1 : 1+64]
-	izero := bytes.IndexByte(folder, 0)
-	if izero < 0 {
-		return folder
-	}
-	return folder[:izero]
-}
-
-func getFile(db dbReader, folder, device, file []byte) (protocol.FileInfo, bool) {
-	nk := deviceKey(folder, device, file)
-	bs, err := db.Get(nk, nil)
+func getFile(db dbReader, key []byte) (protocol.FileInfo, bool) {
+	bs, err := db.Get(key, nil)
 	if err == leveldb.ErrNotFound {
 		return protocol.FileInfo{}, false
 	}
diff --git a/lib/db/leveldb_convert.go b/lib/db/leveldb_convert.go
new file mode 100644
index 000000000..87a4623a7
--- /dev/null
+++ b/lib/db/leveldb_convert.go
@@ -0,0 +1,81 @@
+// Copyright (C) 2015 The Syncthing Authors.
+//
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this file,
+// You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package db
+
+import (
+	"bytes"
+
+	"github.com/syndtr/goleveldb/leveldb"
+)
+
+// ConvertKeyFormat converts from the v0.11 to the v0.12 database format, to
+// avoid having to do rescan. The change is in the key format for folder
+// labels, so we basically just iterate over the database rewriting keys as
+// necessary and then write out the folder ID mapping at the end.
+func ConvertKeyFormat(from, to *leveldb.DB) error {
+	l.Infoln("Converting database key format")
+	files, globals, unchanged := 0, 0, 0
+
+	dbi := newDBInstance(to)
+	i := from.NewIterator(nil, nil)
+	for i.Next() {
+		key := i.Key()
+		switch key[0] {
+		case KeyTypeDevice:
+			newKey := dbi.deviceKey(oldDeviceKeyFolder(key), oldDeviceKeyDevice(key), oldDeviceKeyName(key))
+			if err := to.Put(newKey, i.Value(), nil); err != nil {
+				return err
+			}
+			files++
+		case KeyTypeGlobal:
+			newKey := dbi.globalKey(oldGlobalKeyFolder(key), oldGlobalKeyName(key))
+			if err := to.Put(newKey, i.Value(), nil); err != nil {
+				return err
+			}
+			globals++
+		default:
+			if err := to.Put(key, i.Value(), nil); err != nil {
+				return err
+			}
+			unchanged++
+		}
+	}
+
+	l.Infof("Converted %d files, %d globals (%d unchanged).", files, globals, unchanged)
+
+	return nil
+}
+
+func oldDeviceKeyFolder(key []byte) []byte {
+	folder := key[1 : 1+64]
+	izero := bytes.IndexByte(folder, 0)
+	if izero < 0 {
+		return folder
+	}
+	return folder[:izero]
+}
+
+func oldDeviceKeyDevice(key []byte) []byte {
+	return key[1+64 : 1+64+32]
+}
+
+func oldDeviceKeyName(key []byte) []byte {
+	return key[1+64+32:]
+}
+
+func oldGlobalKeyName(key []byte) []byte {
+	return key[1+64:]
+}
+
+func oldGlobalKeyFolder(key []byte) []byte {
+	folder := key[1 : 1+64]
+	izero := bytes.IndexByte(folder, 0)
+	if izero < 0 {
+		return folder
+	}
+	return folder[:izero]
+}
diff --git a/lib/db/leveldb_dbinstance.go b/lib/db/leveldb_dbinstance.go
index da07d2f28..b5acb42a5 100644
--- a/lib/db/leveldb_dbinstance.go
+++ b/lib/db/leveldb_dbinstance.go
@@ -31,8 +31,8 @@ func newDBInstance(db *leveldb.DB) *dbInstance {
 func (db *dbInstance) genericReplace(folder, device []byte, fs []protocol.FileInfo, localSize, globalSize *sizeTracker, deleteFn deletionHandler) int64 {
 	sort.Sort(fileList(fs)) // sort list on name, same as in the database
 
-	start := deviceKey(folder, device, nil)                            // before all folder/device files
-	limit := deviceKey(folder, device, []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
+	start := db.deviceKey(folder, device, nil)                            // before all folder/device files
+	limit := db.deviceKey(folder, device, []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
 
 	t := db.newReadWriteTransaction()
 	defer t.close()
@@ -58,7 +58,7 @@ func (db *dbInstance) genericReplace(folder, device []byte, fs []protocol.FileIn
 		}
 
 		if moreDb {
-			oldName = deviceKeyName(dbi.Key())
+			oldName = db.deviceKeyName(dbi.Key())
 		}
 
 		cmp := bytes.Compare(newName, oldName)
@@ -146,7 +146,7 @@ func (db *dbInstance) updateFiles(folder, device []byte, fs []protocol.FileInfo,
 	isLocalDevice := bytes.Equal(device, protocol.LocalDeviceID[:])
 	for _, f := range fs {
 		name := []byte(f.Name)
-		fk = deviceKeyInto(fk[:cap(fk)], folder, device, name)
+		fk = db.deviceKeyInto(fk[:cap(fk)], folder, device, name)
 		bs, err := t.Get(fk, nil)
 		if err == leveldb.ErrNotFound {
 			if isLocalDevice {
@@ -196,8 +196,8 @@ func (db *dbInstance) updateFiles(folder, device []byte, fs []protocol.FileInfo,
 }
 
 func (db *dbInstance) withHave(folder, device []byte, truncate bool, fn Iterator) {
-	start := deviceKey(folder, device, nil)                            // before all folder/device files
-	limit := deviceKey(folder, device, []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
+	start := db.deviceKey(folder, device, nil)                            // before all folder/device files
+	limit := db.deviceKey(folder, device, []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
 
 	t := db.newReadOnlyTransaction()
 	defer t.close()
@@ -217,8 +217,8 @@ func (db *dbInstance) withHave(folder, device []byte, truncate bool, fn Iterator
 }
 
 func (db *dbInstance) withAllFolderTruncated(folder []byte, fn func(device []byte, f FileInfoTruncated) bool) {
-	start := deviceKey(folder, nil, nil)                                                  // before all folder/device files
-	limit := deviceKey(folder, protocol.LocalDeviceID[:], []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
+	start := db.deviceKey(folder, nil, nil)                                                  // before all folder/device files
+	limit := db.deviceKey(folder, protocol.LocalDeviceID[:], []byte{0xff, 0xff, 0xff, 0xff}) // after all folder/device files
 
 	t := db.newReadWriteTransaction()
 	defer t.close()
@@ -227,7 +227,7 @@ func (db *dbInstance) withAllFolderTruncated(folder []byte, fn func(device []byt
 	defer dbi.Release()
 
 	for dbi.Next() {
-		device := deviceKeyDevice(dbi.Key())
+		device := db.deviceKeyDevice(dbi.Key())
 		var f FileInfoTruncated
 		err := f.UnmarshalXDR(dbi.Value())
 		if err != nil {
@@ -250,11 +250,11 @@ func (db *dbInstance) withAllFolderTruncated(folder []byte, fn func(device []byt
 }
 
 func (db *dbInstance) getFile(folder, device, file []byte) (protocol.FileInfo, bool) {
-	return getFile(db, folder, device, file)
+	return getFile(db, db.deviceKey(folder, device, file))
 }
 
 func (db *dbInstance) getGlobal(folder, file []byte, truncate bool) (FileIntf, bool) {
-	k := globalKey(folder, file)
+	k := db.globalKey(folder, file)
 
 	t := db.newReadOnlyTransaction()
 	defer t.close()
@@ -277,7 +277,7 @@ func (db *dbInstance) getGlobal(folder, file []byte, truncate bool) (FileIntf, b
 		panic("no versions?")
 	}
 
-	k = deviceKey(folder, vl.versions[0].device, file)
+	k = db.deviceKey(folder, vl.versions[0].device, file)
 	bs, err = t.Get(k, nil)
 	if err != nil {
 		panic(err)
@@ -294,7 +294,7 @@ func (db *dbInstance) withGlobal(folder, prefix []byte, truncate bool, fn Iterat
 	t := db.newReadOnlyTransaction()
 	defer t.close()
 
-	dbi := t.NewIterator(util.BytesPrefix(globalKey(folder, prefix)), nil)
+	dbi := t.NewIterator(util.BytesPrefix(db.globalKey(folder, prefix)), nil)
 	defer dbi.Release()
 
 	var fk []byte
@@ -308,8 +308,8 @@ func (db *dbInstance) withGlobal(folder, prefix []byte, truncate bool, fn Iterat
 			l.Debugln(dbi.Key())
 			panic("no versions?")
 		}
-		name := globalKeyName(dbi.Key())
-		fk = deviceKeyInto(fk[:cap(fk)], folder, vl.versions[0].device, name)
+		name := db.globalKeyName(dbi.Key())
+		fk = db.deviceKeyInto(fk[:cap(fk)], folder, vl.versions[0].device, name)
 		bs, err := t.Get(fk, nil)
 		if err != nil {
 			l.Debugf("folder: %q (%x)", folder, folder)
@@ -334,7 +334,7 @@ func (db *dbInstance) withGlobal(folder, prefix []byte, truncate bool, fn Iterat
 }
 
 func (db *dbInstance) availability(folder, file []byte) []protocol.DeviceID {
-	k := globalKey(folder, file)
+	k := db.globalKey(folder, file)
 	bs, err := db.Get(k, nil)
 	if err == leveldb.ErrNotFound {
 		return nil
@@ -362,8 +362,8 @@ func (db *dbInstance) availability(folder, file []byte) []protocol.DeviceID {
 }
 
 func (db *dbInstance) withNeed(folder, device []byte, truncate bool, fn Iterator) {
-	start := globalKey(folder, nil)
-	limit := globalKey(folder, []byte{0xff, 0xff, 0xff, 0xff})
+	start := db.globalKey(folder, nil)
+	limit := db.globalKey(folder, []byte{0xff, 0xff, 0xff, 0xff})
 
 	t := db.newReadOnlyTransaction()
 	defer t.close()
@@ -400,7 +400,7 @@ nextFile:
 		}
 
 		if need || !have {
-			name := globalKeyName(dbi.Key())
+			name := db.globalKeyName(dbi.Key())
 			needVersion := vl.versions[0].version
 
 		nextVersion:
@@ -409,7 +409,7 @@ nextFile:
 					// We haven't found a valid copy of the file with the needed version.
 					continue nextFile
 				}
-				fk = deviceKeyInto(fk[:cap(fk)], folder, vl.versions[i].device, name)
+				fk = db.deviceKeyInto(fk[:cap(fk)], folder, vl.versions[i].device, name)
 				bs, err := t.Get(fk, nil)
 				if err != nil {
 					var id protocol.DeviceID
@@ -461,7 +461,7 @@ func (db *dbInstance) listFolders() []string {
 
 	folderExists := make(map[string]bool)
 	for dbi.Next() {
-		folder := string(globalKeyFolder(dbi.Key()))
+		folder := string(db.globalKeyFolder(dbi.Key()))
 		if !folderExists[folder] {
 			folderExists[folder] = true
 		}
@@ -483,7 +483,7 @@ func (db *dbInstance) dropFolder(folder []byte) {
 	// Remove all items related to the given folder from the device->file bucket
 	dbi := t.NewIterator(util.BytesPrefix([]byte{KeyTypeDevice}), nil)
 	for dbi.Next() {
-		itemFolder := deviceKeyFolder(dbi.Key())
+		itemFolder := db.deviceKeyFolder(dbi.Key())
 		if bytes.Compare(folder, itemFolder) == 0 {
 			db.Delete(dbi.Key(), nil)
 		}
@@ -493,7 +493,7 @@ func (db *dbInstance) dropFolder(folder []byte) {
 	// Remove all items related to the given folder from the global bucket
 	dbi = t.NewIterator(util.BytesPrefix([]byte{KeyTypeGlobal}), nil)
 	for dbi.Next() {
-		itemFolder := globalKeyFolder(dbi.Key())
+		itemFolder := db.globalKeyFolder(dbi.Key())
 		if bytes.Compare(folder, itemFolder) == 0 {
 			db.Delete(dbi.Key(), nil)
 		}
@@ -505,8 +505,8 @@ func (db *dbInstance) checkGlobals(folder []byte, globalSize *sizeTracker) {
 	t := db.newReadWriteTransaction()
 	defer t.close()
 
-	start := globalKey(folder, nil)
-	limit := globalKey(folder, []byte{0xff, 0xff, 0xff, 0xff})
+	start := db.globalKey(folder, nil)
+	limit := db.globalKey(folder, []byte{0xff, 0xff, 0xff, 0xff})
 	dbi := t.NewIterator(&util.Range{Start: start, Limit: limit}, nil)
 	defer dbi.Release()
 
@@ -524,10 +524,10 @@ func (db *dbInstance) checkGlobals(folder []byte, globalSize *sizeTracker) {
 		// there are global entries pointing to no longer existing files. Here
 		// we find those and clear them out.
 
-		name := globalKeyName(gk)
+		name := db.globalKeyName(gk)
 		var newVL versionList
 		for i, version := range vl.versions {
-			fk = deviceKeyInto(fk[:cap(fk)], folder, version.device, name)
+			fk = db.deviceKeyInto(fk[:cap(fk)], folder, version.device, name)
 
 			_, err := t.Get(fk, nil)
 			if err == leveldb.ErrNotFound {
@@ -555,6 +555,75 @@ func (db *dbInstance) checkGlobals(folder []byte, globalSize *sizeTracker) {
 	l.Debugf("db check completed for %q", folder)
 }
 
+// deviceKey returns a byte slice encoding the following information:
+//	   keyTypeDevice (1 byte)
+//	   folder (64 bytes)
+//	   device (32 bytes)
+//	   name (variable size)
+func (db *dbInstance) deviceKey(folder, device, file []byte) []byte {
+	return db.deviceKeyInto(nil, folder, device, file)
+}
+
+func (db *dbInstance) deviceKeyInto(k []byte, folder, device, file []byte) []byte {
+	reqLen := 1 + 64 + 32 + len(file)
+	if len(k) < reqLen {
+		k = make([]byte, reqLen)
+	}
+	k[0] = KeyTypeDevice
+	if len(folder) > 64 {
+		panic("folder name too long")
+	}
+	copy(k[1:], []byte(folder))
+	copy(k[1+64:], device[:])
+	copy(k[1+64+32:], []byte(file))
+	return k[:reqLen]
+}
+
+func (db *dbInstance) deviceKeyName(key []byte) []byte {
+	return key[1+64+32:]
+}
+
+func (db *dbInstance) deviceKeyFolder(key []byte) []byte {
+	folder := key[1 : 1+64]
+	izero := bytes.IndexByte(folder, 0)
+	if izero < 0 {
+		return folder
+	}
+	return folder[:izero]
+}
+
+func (db *dbInstance) deviceKeyDevice(key []byte) []byte {
+	return key[1+64 : 1+64+32]
+}
+
+// globalKey returns a byte slice encoding the following information:
+//	   keyTypeGlobal (1 byte)
+//	   folder (64 bytes)
+//	   name (variable size)
+func (db *dbInstance) globalKey(folder, file []byte) []byte {
+	k := make([]byte, 1+64+len(file))
+	k[0] = KeyTypeGlobal
+	if len(folder) > 64 {
+		panic("folder name too long")
+	}
+	copy(k[1:], []byte(folder))
+	copy(k[1+64:], []byte(file))
+	return k
+}
+
+func (db *dbInstance) globalKeyName(key []byte) []byte {
+	return key[1+64:]
+}
+
+func (db *dbInstance) globalKeyFolder(key []byte) []byte {
+	folder := key[1 : 1+64]
+	izero := bytes.IndexByte(folder, 0)
+	if izero < 0 {
+		return folder
+	}
+	return folder[:izero]
+}
+
 func unmarshalTrunc(bs []byte, truncate bool) (FileIntf, error) {
 	if truncate {
 		var tf FileInfoTruncated
diff --git a/lib/db/leveldb_test.go b/lib/db/leveldb_test.go
index 57393cda0..2bd020ed8 100644
--- a/lib/db/leveldb_test.go
+++ b/lib/db/leveldb_test.go
@@ -16,17 +16,19 @@ func TestDeviceKey(t *testing.T) {
 	dev := []byte("device67890123456789012345678901")
 	name := []byte("name")
 
-	key := deviceKey(fld, dev, name)
+	db := &dbInstance{}
 
-	fld2 := deviceKeyFolder(key)
+	key := db.deviceKey(fld, dev, name)
+
+	fld2 := db.deviceKeyFolder(key)
 	if bytes.Compare(fld2, fld) != 0 {
 		t.Errorf("wrong folder %q != %q", fld2, fld)
 	}
-	dev2 := deviceKeyDevice(key)
+	dev2 := db.deviceKeyDevice(key)
 	if bytes.Compare(dev2, dev) != 0 {
 		t.Errorf("wrong device %q != %q", dev2, dev)
 	}
-	name2 := deviceKeyName(key)
+	name2 := db.deviceKeyName(key)
 	if bytes.Compare(name2, name) != 0 {
 		t.Errorf("wrong name %q != %q", name2, name)
 	}
@@ -36,13 +38,15 @@ func TestGlobalKey(t *testing.T) {
 	fld := []byte("folder6789012345678901234567890123456789012345678901234567890123")
 	name := []byte("name")
 
-	key := globalKey(fld, name)
+	db := &dbInstance{}
 
-	fld2 := globalKeyFolder(key)
+	key := db.globalKey(fld, name)
+
+	fld2 := db.globalKeyFolder(key)
 	if bytes.Compare(fld2, fld) != 0 {
 		t.Errorf("wrong folder %q != %q", fld2, fld)
 	}
-	name2 := globalKeyName(key)
+	name2 := db.globalKeyName(key)
 	if bytes.Compare(name2, name) != 0 {
 		t.Errorf("wrong name %q != %q", name2, name)
 	}
diff --git a/lib/db/leveldb_transactions.go b/lib/db/leveldb_transactions.go
index 24e9af0fe..f4ab2cb4b 100644
--- a/lib/db/leveldb_transactions.go
+++ b/lib/db/leveldb_transactions.go
@@ -16,7 +16,7 @@ import (
 // A readOnlyTransaction represents a database snapshot.
 type readOnlyTransaction struct {
 	*leveldb.Snapshot
-	db *leveldb.DB
+	db *dbInstance
 }
 
 func (db *dbInstance) newReadOnlyTransaction() readOnlyTransaction {
@@ -26,7 +26,7 @@ func (db *dbInstance) newReadOnlyTransaction() readOnlyTransaction {
 	}
 	return readOnlyTransaction{
 		Snapshot: snap,
-		db:       db.DB,
+		db:       db,
 	}
 }
 
@@ -35,7 +35,7 @@ func (t readOnlyTransaction) close() {
 }
 
 func (t readOnlyTransaction) getFile(folder, device, file []byte) (protocol.FileInfo, bool) {
-	return getFile(t, folder, device, file)
+	return getFile(t, t.db.deviceKey(folder, device, file))
 }
 
 // A readWriteTransaction is a readOnlyTransaction plus a batch for writes.
@@ -78,7 +78,7 @@ func (t readWriteTransaction) insertFile(folder, device []byte, file protocol.Fi
 	}
 
 	name := []byte(file.Name)
-	nk := deviceKey(folder, device, name)
+	nk := t.db.deviceKey(folder, device, name)
 	t.Put(nk, file.MustMarshalXDR())
 
 	return file.LocalVersion
@@ -90,7 +90,7 @@ func (t readWriteTransaction) insertFile(folder, device []byte, file protocol.Fi
 func (t readWriteTransaction) updateGlobal(folder, device []byte, file protocol.FileInfo, globalSize *sizeTracker) bool {
 	l.Debugf("update global; folder=%q device=%v file=%q version=%d", folder, protocol.DeviceIDFromBytes(device), file.Name, file.Version)
 	name := []byte(file.Name)
-	gk := globalKey(folder, name)
+	gk := t.db.globalKey(folder, name)
 	svl, err := t.Get(gk, nil)
 	if err != nil && err != leveldb.ErrNotFound {
 		panic(err)
@@ -197,7 +197,7 @@ done:
 func (t readWriteTransaction) removeFromGlobal(folder, device, file []byte, globalSize *sizeTracker) {
 	l.Debugf("remove from global; folder=%q device=%v file=%q", folder, protocol.DeviceIDFromBytes(device), file)
 
-	gk := globalKey(folder, file)
+	gk := t.db.globalKey(folder, file)
 	svl, err := t.Get(gk, nil)
 	if err != nil {
 		// We might be called to "remove" a global version that doesn't exist