diff --git a/swh/loader/git/converters.py b/swh/loader/git/converters.py
--- a/swh/loader/git/converters.py
+++ b/swh/loader/git/converters.py
@@ -185,6 +185,7 @@
 
     author_timezone = None
     committer_timezone = None
+    assert commit._chunked_text is not None  # to keep mypy happy
     for (field, value) in _parse_message(commit._chunked_text):
         if field == b"author":
             m = AUTHORSHIP_LINE_RE.match(value)
diff --git a/swh/loader/git/dumb.py b/swh/loader/git/dumb.py
--- a/swh/loader/git/dumb.py
+++ b/swh/loader/git/dumb.py
@@ -86,7 +86,7 @@
         commit_objects = []
         for ref in wants:
             ref_object = self._get_git_object(ref)
-            if ref_object.get_type() == Commit.type_num:
+            if ref_object.type_num == Commit.type_num:
                 commit_objects.append(cast(Commit, ref_object))
                 self.objects[b"commit"].add(ref)
             else: