diff --git a/lib/db/leveldb_dbinstance.go b/lib/db/leveldb_dbinstance.go
index 75a411e8..b066eb4c 100644
--- a/lib/db/leveldb_dbinstance.go
+++ b/lib/db/leveldb_dbinstance.go
@@ -206,33 +206,23 @@ func (db *Instance) updateFiles(folder, device []byte, fs []protocol.FileInfo, l
 			err = ef.Unmarshal(bs)
 		}
 
-		if err != nil {
-			if isLocalDevice {
-				localSize.addFile(f)
-			}
-
-			t.insertFile(folder, device, f)
-			if f.IsInvalid() {
-				t.removeFromGlobal(folder, device, name, globalSize)
-			} else {
-				t.updateGlobal(folder, device, f, globalSize)
-			}
+		// The Invalid flag might change without the version being bumped.
+		if err == nil && ef.Version.Equal(f.Version) && ef.Invalid == f.Invalid {
 			continue
 		}
 
-		// The Invalid flag might change without the version being bumped.
-		if !ef.Version.Equal(f.Version) || ef.Invalid != f.Invalid {
-			if isLocalDevice {
+		if isLocalDevice {
+			if err == nil {
 				localSize.removeFile(ef)
-				localSize.addFile(f)
 			}
+			localSize.addFile(f)
+		}
 
-			t.insertFile(folder, device, f)
-			if f.IsInvalid() {
-				t.removeFromGlobal(folder, device, name, globalSize)
-			} else {
-				t.updateGlobal(folder, device, f, globalSize)
-			}
+		t.insertFile(folder, device, f)
+		if f.IsInvalid() {
+			t.removeFromGlobal(folder, device, name, globalSize)
+		} else {
+			t.updateGlobal(folder, device, f, globalSize)
 		}
 
 		// Write out and reuse the batch every few records, to avoid the batch
@@ -440,7 +430,6 @@ func (db *Instance) withNeed(folder, device []byte, truncate bool, fn Iterator)
 	defer dbi.Release()
 
 	var fk []byte
-nextFile:
 	for dbi.Next() {
 		var vl VersionList
 		err := vl.Unmarshal(dbi.Value())
@@ -468,48 +457,49 @@ nextFile:
 			}
 		}
 
-		if need || !have {
-			name := db.globalKeyName(dbi.Key())
-			needVersion := vl.Versions[0].Version
+		if have && !need {
+			continue
+		}
 
-		nextVersion:
-			for i := range vl.Versions {
-				if !vl.Versions[i].Version.Equal(needVersion) {
-					// We haven't found a valid copy of the file with the needed version.
-					continue nextFile
-				}
-				fk = db.deviceKeyInto(fk[:cap(fk)], folder, vl.Versions[i].Device, name)
-				bs, err := t.Get(fk, nil)
-				if err != nil {
-					l.Debugln("surprise error:", err)
-					continue nextVersion
-				}
+		name := db.globalKeyName(dbi.Key())
+		needVersion := vl.Versions[0].Version
 
-				gf, err := unmarshalTrunc(bs, truncate)
-				if err != nil {
-					l.Debugln("unmarshal error:", err)
-					continue nextVersion
-				}
-
-				if gf.IsInvalid() {
-					// The file is marked invalid for whatever reason, don't use it.
-					continue nextVersion
-				}
-
-				if gf.IsDeleted() && !have {
-					// We don't need deleted files that we don't have
-					continue nextFile
-				}
-
-				l.Debugf("need folder=%q device=%v name=%q need=%v have=%v haveV=%d globalV=%d", folder, protocol.DeviceIDFromBytes(device), name, need, have, haveVersion, vl.Versions[0].Version)
-
-				if cont := fn(gf); !cont {
-					return
-				}
-
-				// This file is handled, no need to look further in the version list
-				continue nextFile
+		for i := range vl.Versions {
+			if !vl.Versions[i].Version.Equal(needVersion) {
+				// We haven't found a valid copy of the file with the needed version.
+				break
 			}
+			fk = db.deviceKeyInto(fk[:cap(fk)], folder, vl.Versions[i].Device, name)
+			bs, err := t.Get(fk, nil)
+			if err != nil {
+				l.Debugln("surprise error:", err)
+				continue
+			}
+
+			gf, err := unmarshalTrunc(bs, truncate)
+			if err != nil {
+				l.Debugln("unmarshal error:", err)
+				continue
+			}
+
+			if gf.IsInvalid() {
+				// The file is marked invalid for whatever reason, don't use it.
+				continue
+			}
+
+			if gf.IsDeleted() && !have {
+				// We don't need deleted files that we don't have
+				break
+			}
+
+			l.Debugf("need folder=%q device=%v name=%q need=%v have=%v haveV=%d globalV=%d", folder, protocol.DeviceIDFromBytes(device), name, need, have, haveVersion, vl.Versions[0].Version)
+
+			if cont := fn(gf); !cont {
+				return
+			}
+
+			// This file is handled, no need to look further in the version list
+			break
 		}
 	}
 }
diff --git a/lib/db/set.go b/lib/db/set.go
index 9bfbd0fb..efdcc24f 100644
--- a/lib/db/set.go
+++ b/lib/db/set.go
@@ -182,13 +182,19 @@ func (s *FileSet) Update(device protocol.DeviceID, fs []protocol.FileInfo) {
 	if device == protocol.LocalDeviceID {
 		discards := make([]protocol.FileInfo, 0, len(fs))
 		updates := make([]protocol.FileInfo, 0, len(fs))
-		for i, newFile := range fs {
-			fs[i].Sequence = atomic.AddInt64(&s.sequence, 1)
-			existingFile, ok := s.db.getFile([]byte(s.folder), device[:], []byte(newFile.Name))
-			if !ok || !existingFile.Version.Equal(newFile.Version) {
-				discards = append(discards, existingFile)
-				updates = append(updates, newFile)
+		// db.UpdateFiles will sort unchanged files out -> save one db lookup
+		// filter slice according to https://github.com/golang/go/wiki/SliceTricks#filtering-without-allocating
+		oldFs := fs
+		fs = fs[:0]
+		for _, nf := range oldFs {
+			ef, ok := s.db.getFile([]byte(s.folder), device[:], []byte(nf.Name))
+			if ok && ef.Version.Equal(nf.Version) && ef.Invalid == nf.Invalid {
+				continue
 			}
+			nf.Sequence = atomic.AddInt64(&s.sequence, 1)
+			fs = append(fs, nf)
+			discards = append(discards, ef)
+			updates = append(updates, nf)
 		}
 		s.blockmap.Discard(discards)
 		s.blockmap.Update(updates)
diff --git a/lib/db/set_test.go b/lib/db/set_test.go
index d21e76c9..7ef5d51f 100644
--- a/lib/db/set_test.go
+++ b/lib/db/set_test.go
@@ -350,13 +350,16 @@ func TestNeedWithInvalid(t *testing.T) {
 func TestUpdateToInvalid(t *testing.T) {
 	ldb := db.OpenMemory()
 
-	s := db.NewFileSet("test)", fs.NewFilesystem(fs.FilesystemTypeBasic, "."), ldb)
+	folder := "test)"
+	s := db.NewFileSet(folder, fs.NewFilesystem(fs.FilesystemTypeBasic, "."), ldb)
+	f := db.NewBlockFinder(ldb)
 
 	localHave := fileList{
 		protocol.FileInfo{Name: "a", Version: protocol.Vector{Counters: []protocol.Counter{{ID: myID, Value: 1000}}}, Blocks: genBlocks(1)},
 		protocol.FileInfo{Name: "b", Version: protocol.Vector{Counters: []protocol.Counter{{ID: myID, Value: 1001}}}, Blocks: genBlocks(2)},
 		protocol.FileInfo{Name: "c", Version: protocol.Vector{Counters: []protocol.Counter{{ID: myID, Value: 1002}}}, Blocks: genBlocks(5), Invalid: true},
 		protocol.FileInfo{Name: "d", Version: protocol.Vector{Counters: []protocol.Counter{{ID: myID, Value: 1003}}}, Blocks: genBlocks(7)},
+		protocol.FileInfo{Name: "e", Version: protocol.Vector{Counters: []protocol.Counter{{ID: myID, Value: 1003}}}, Invalid: true},
 	}
 
 	s.Replace(protocol.LocalDeviceID, localHave)
@@ -368,8 +371,12 @@ func TestUpdateToInvalid(t *testing.T) {
 		t.Errorf("Have incorrect before invalidation;\n A: %v !=\n E: %v", have, localHave)
 	}
 
-	localHave[1] = protocol.FileInfo{Name: "b", Version: protocol.Vector{Counters: []protocol.Counter{{ID: myID, Value: 1001}}}, Invalid: true}
-	s.Update(protocol.LocalDeviceID, localHave[1:2])
+	oldBlockHash := localHave[1].Blocks[0].Hash
+	localHave[1].Invalid = true
+	localHave[1].Blocks = nil
+	localHave[4].Invalid = false
+	localHave[4].Blocks = genBlocks(3)
+	s.Update(protocol.LocalDeviceID, append(fileList{}, localHave[1], localHave[4]))
 
 	have = fileList(haveList(s, protocol.LocalDeviceID))
 	sort.Sort(have)
@@ -377,6 +384,23 @@ func TestUpdateToInvalid(t *testing.T) {
 	if fmt.Sprint(have) != fmt.Sprint(localHave) {
 		t.Errorf("Have incorrect after invalidation;\n A: %v !=\n E: %v", have, localHave)
 	}
+
+	f.Iterate([]string{folder}, oldBlockHash, func(folder, file string, index int32) bool {
+		if file == localHave[1].Name {
+			t.Errorf("Found unexpected block in blockmap for invalidated file")
+			return true
+		}
+		return false
+	})
+
+	if !f.Iterate([]string{folder}, localHave[4].Blocks[0].Hash, func(folder, file string, index int32) bool {
+		if file == localHave[4].Name {
+			return true
+		}
+		return false
+	}) {
+		t.Errorf("First block of un-invalidated file is missing from blockmap")
+	}
 }
 
 func TestInvalidAvailability(t *testing.T) {