diff --git a/go/storage/volume.go b/go/storage/volume.go
index 59c3055e3..69817a6d4 100644
--- a/go/storage/volume.go
+++ b/go/storage/volume.go
@@ -370,12 +370,12 @@ func (v *Volume) copyDataAndGenerateIndexFile(dstName, idxName string) (err erro
 	var (
 		dst, idx *os.File
 	)
-	if dst, err = os.OpenFile(dstName, os.O_WRONLY|os.O_CREATE, 0644); err != nil {
+	if dst, err = os.OpenFile(dstName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
 		return
 	}
 	defer dst.Close()
 
-	if idx, err = os.OpenFile(idxName, os.O_WRONLY|os.O_CREATE, 0644); err != nil {
+	if idx, err = os.OpenFile(idxName, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644); err != nil {
 		return
 	}
 	defer idx.Close()
diff --git a/go/weed/fix.go b/go/weed/fix.go
index 159e2dbde..3c09727c1 100644
--- a/go/weed/fix.go
+++ b/go/weed/fix.go
@@ -37,7 +37,7 @@ func runFix(cmd *Command, args []string) bool {
 	if *fixVolumeCollection != "" {
 		fileName = *fixVolumeCollection + "_" + fileName
 	}
-	indexFile, err := os.OpenFile(path.Join(*fixVolumePath, fileName+".idx"), os.O_WRONLY|os.O_CREATE, 0644)
+	indexFile, err := os.OpenFile(path.Join(*fixVolumePath, fileName+".idx"), os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0644)
 	if err != nil {
 		glog.Fatalf("Create Volume Index [ERROR] %s\n", err)
 	}