diff --git a/sda/internal/helper/helper.go b/sda/internal/helper/helper.go
index ff88236da4..1026a62980 100644
--- a/sda/internal/helper/helper.go
+++ b/sda/internal/helper/helper.go
@@ -458,9 +458,11 @@ func AnonymizeFilepath(fp string, username string) string {
 }
 
 func UnanonymizeFilepath(fp string, username string) string {
-	if strings.HasPrefix(fp, strings.Replace(username, "@", "_", 1)) {
+	sanitized := strings.Replace(username, "@", "_", 1)
+	sep := string(os.PathSeparator)
+	if fp == sanitized || strings.HasPrefix(fp, sanitized+sep) || fp == username || strings.HasPrefix(fp, username+sep) {
 		return fp
 	}
 
-	return filepath.Join(strings.Replace(username, "@", "_", 1), fp)
+	return filepath.Join(sanitized, fp)
 }
diff --git a/sda/internal/helper/helper_test.go b/sda/internal/helper/helper_test.go
index 06b1dedb52..d99065a2f6 100644
--- a/sda/internal/helper/helper_test.go
+++ b/sda/internal/helper/helper_test.go
@@ -179,3 +179,17 @@ func (ts *HelperTest) TestUnanonymizeFilepath_oldMessage() {
 	newPath := UnanonymizeFilepath(filePath, userName)
 	assert.Equal(ts.T(), filePath, newPath)
 }
+
+func (ts *HelperTest) TestUnanonymizeFilepath_rawUsernamePrefix() {
+	filePath := "test.user@demo.org/main_folder/sub_folder/file.name"
+	userName := "test.user@demo.org"
+	newPath := UnanonymizeFilepath(filePath, userName)
+	assert.Equal(ts.T(), filePath, newPath)
+}
+
+func (ts *HelperTest) TestUnanonymizeFilepath_bareFileNameStartingWithUsername() {
+	filePath := "test.user@demo.org_report.name"
+	userName := "test.user@demo.org"
+	newPath := UnanonymizeFilepath(filePath, userName)
+	assert.Equal(ts.T(), filepath.Join(strings.Replace(userName, "@", "_", 1), filePath), newPath)
+}