diff --git a/mercurial/bundlerepo.py b/mercurial/bundlerepo.py
index 90f047edab4fc156e6feec91c5604548681abe4e_bWVyY3VyaWFsL2J1bmRsZXJlcG8ucHk=..562f7da122b590ccd8de10da9b413110975e5a0b_bWVyY3VyaWFsL2J1bmRsZXJlcG8ucHk= 100644
--- a/mercurial/bundlerepo.py
+++ b/mercurial/bundlerepo.py
@@ -88,7 +88,7 @@
                     )
 
             if not self.index.has_node(deltabase):
-                raise LookupError(
+                raise error.LookupError(
                     deltabase, self.display_id, _(b'unknown delta base')
                 )