diff --git a/pack.go b/pack.go
index 20f18f0..2ba42f8 100644
--- a/pack.go
+++ b/pack.go
@@ -199,6 +199,7 @@ func (wft *walkFileTree) virPath(fpath string) string {
 		return ""
 	}
 	name = name[1:]
+	name = path.ToSlash(name)
 	return name
 }