diff --git a/contrib/python3-whitelist b/contrib/python3-whitelist
--- a/contrib/python3-whitelist
+++ b/contrib/python3-whitelist
@@ -526,6 +526,7 @@
 test-relink.t
 test-remotefilelog-bad-configs.t
 test-remotefilelog-blame.t
+test-remotefilelog-bundles.t
 test-remotefilelog-clone-tree.t
 test-remotefilelog-clone.t
 test-remotefilelog-keepset.t
diff --git a/hgext/remotefilelog/shallowbundle.py b/hgext/remotefilelog/shallowbundle.py
--- a/hgext/remotefilelog/shallowbundle.py
+++ b/hgext/remotefilelog/shallowbundle.py
@@ -15,6 +15,7 @@
     match,
     mdiff,
     pycompat,
+    util,
 )
 from . import (
     constants,
@@ -269,7 +270,7 @@
 
         base = fl.revision(deltabase, raw=True)
         text = mdiff.patch(base, delta)
-        if isinstance(text, buffer):
+        if isinstance(text, util.buffer):
             text = str(text)
 
         meta, text = shallowutil.parsemeta(text)