diff --git a/src/storage/file/id.rs b/src/storage/file/id.rs
index bdfd9db4..d26b537b 100644
--- a/src/storage/file/id.rs
+++ b/src/storage/file/id.rs
@@ -105,7 +105,7 @@ impl Into<String> for FileID {
     fn into(self) -> String {
         let typestr : String = self.id_type.into();
         let idstr   : String = self.id.into();
-        typestr + &idstr[..]
+        typestr + "-" + &idstr[..]
     }
 }