diff --git a/scanner/change_detector.go b/scanner/change_detector.go
index dde337fb2..159c7a446 100644
--- a/scanner/change_detector.go
+++ b/scanner/change_detector.go
@@ -9,22 +9,28 @@ import (
 	"github.com/cloudsonic/sonic-server/log"
 )
 
+type dirInfo struct {
+	mdate time.Time
+	maybe bool
+}
+type dirInfoMap map[string]dirInfo
+
 type ChangeDetector struct {
 	rootFolder string
-	dirMap     map[string]time.Time
+	dirMap     dirInfoMap
 }
 
 func NewChangeDetector(rootFolder string) *ChangeDetector {
 	return &ChangeDetector{
 		rootFolder: rootFolder,
-		dirMap:     map[string]time.Time{},
+		dirMap:     dirInfoMap{},
 	}
 }
 
 func (s *ChangeDetector) Scan(lastModifiedSince time.Time) (changed []string, deleted []string, err error) {
 	start := time.Now()
-	newMap := make(map[string]time.Time)
-	err = s.loadMap(s.rootFolder, newMap)
+	newMap := make(dirInfoMap)
+	err = s.loadMap(newMap, s.rootFolder, lastModifiedSince, false)
 	if err != nil {
 		return
 	}
@@ -67,20 +73,21 @@ func (s *ChangeDetector) loadDir(dirPath string) (children []string, lastUpdated
 	return
 }
 
-func (s *ChangeDetector) loadMap(rootPath string, dirMap map[string]time.Time) error {
+func (s *ChangeDetector) loadMap(dirMap dirInfoMap, rootPath string, since time.Time, maybe bool) error {
 	children, lastUpdated, err := s.loadDir(rootPath)
 	if err != nil {
 		return err
 	}
+	maybe = maybe || lastUpdated.After(since)
 	for _, c := range children {
-		err := s.loadMap(c, dirMap)
+		err := s.loadMap(dirMap, c, since, maybe)
 		if err != nil {
 			return err
 		}
 	}
 
 	dir := s.getRelativePath(rootPath)
-	dirMap[dir] = lastUpdated
+	dirMap[dir] = dirInfo{mdate: lastUpdated, maybe: maybe}
 
 	return nil
 }
@@ -93,11 +100,16 @@ func (s *ChangeDetector) getRelativePath(subfolder string) string {
 	return dir
 }
 
-func (s *ChangeDetector) checkForUpdates(lastModifiedSince time.Time, newMap map[string]time.Time) (changed []string, deleted []string, err error) {
-	for dir, lastUpdated := range newMap {
-		oldLastUpdated, ok := s.dirMap[dir]
-		if !ok {
-			oldLastUpdated = lastModifiedSince
+func (s *ChangeDetector) checkForUpdates(lastModifiedSince time.Time, newMap dirInfoMap) (changed []string, deleted []string, err error) {
+	for dir, newEntry := range newMap {
+		lastUpdated := newEntry.mdate
+		oldLastUpdated := lastModifiedSince
+		if oldEntry, ok := s.dirMap[dir]; ok {
+			oldLastUpdated = oldEntry.mdate
+		} else {
+			if newEntry.maybe {
+				oldLastUpdated = time.Time{}
+			}
 		}
 		if lastUpdated.After(oldLastUpdated) {
 			changed = append(changed, dir)
diff --git a/scanner/change_detector_test.go b/scanner/change_detector_test.go
index 2ec621fba..7d8ed4ec6 100644
--- a/scanner/change_detector_test.go
+++ b/scanner/change_detector_test.go
@@ -33,6 +33,7 @@ var _ = Describe("ChangeDetector", func() {
 		Expect(changed).To(ConsistOf("."))
 
 		// Add one subfolder
+		lastModifiedSince = time.Now()
 		err = os.MkdirAll(path.Join(testFolder, "a"), 0700)
 		if err != nil {
 			panic(err)
@@ -43,6 +44,7 @@ var _ = Describe("ChangeDetector", func() {
 		Expect(changed).To(ConsistOf(".", "/a"))
 
 		// Add more subfolders
+		lastModifiedSince = time.Now()
 		err = os.MkdirAll(path.Join(testFolder, "a", "b", "c"), 0700)
 		if err != nil {
 			panic(err)
@@ -53,12 +55,14 @@ var _ = Describe("ChangeDetector", func() {
 		Expect(changed).To(ConsistOf("/a", "/a/b", "/a/b/c"))
 
 		// Scan with no changes
+		lastModifiedSince = time.Now()
 		changed, deleted, err = scanner.Scan(lastModifiedSince)
 		Expect(err).To(BeNil())
 		Expect(deleted).To(BeEmpty())
 		Expect(changed).To(BeEmpty())
 
 		// New file in subfolder
+		lastModifiedSince = time.Now()
 		_, err = os.Create(path.Join(testFolder, "a", "b", "empty.txt"))
 		if err != nil {
 			panic(err)
@@ -69,6 +73,7 @@ var _ = Describe("ChangeDetector", func() {
 		Expect(changed).To(ConsistOf("/a/b"))
 
 		// Delete file in subfolder
+		lastModifiedSince = time.Now()
 		err = os.Remove(path.Join(testFolder, "a", "b", "empty.txt"))
 		if err != nil {
 			panic(err)
@@ -79,6 +84,7 @@ var _ = Describe("ChangeDetector", func() {
 		Expect(changed).To(ConsistOf("/a/b"))
 
 		// Delete subfolder
+		lastModifiedSince = time.Now()
 		err = os.Remove(path.Join(testFolder, "a", "b", "c"))
 		if err != nil {
 			panic(err)
@@ -97,7 +103,8 @@ var _ = Describe("ChangeDetector", func() {
 		Expect(changed).To(BeEmpty())
 		Expect(changed).To(BeEmpty())
 
-		_, err = os.Create(path.Join(testFolder, "a", "b", "new.txt"))
+		f, err := os.Create(path.Join(testFolder, "a", "b", "new.txt"))
+		f.Close()
 		changed, deleted, err = newScanner.Scan(lastModifiedSince)
 		Expect(err).To(BeNil())
 		Expect(deleted).To(BeEmpty())