diff --git a/core/backup_create.go b/core/backup_create.go
index 715ecd3c..e0c199a5 100644
--- a/core/backup_create.go
+++ b/core/backup_create.go
@@ -322,6 +322,9 @@ func newZipWriter(zipFilePath string) (*zipWriter, error) {
 }
 
 func (z *zipWriter) close() error {
+	z.mu.Lock()
+	defer z.mu.Unlock()
+
 	var wErr, fErr error
 
 	if z.w != nil {