diff --git a/requirements-swh.txt b/requirements-swh.txt
--- a/requirements-swh.txt
+++ b/requirements-swh.txt
@@ -1,4 +1,4 @@
-swh.storage <= 0.9.3
-swh.model < 0.4.0
+swh.storage >= 0.10.0
+swh.model >= 0.4.0
 swh.scheduler >= 0.0.39
 swh.loader.core >= 0.5.2
diff --git a/swh/loader/svn/converters.py b/swh/loader/svn/converters.py
--- a/swh/loader/svn/converters.py
+++ b/swh/loader/svn/converters.py
@@ -3,7 +3,7 @@
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
 
-from typing import Any, Dict, Optional, Sequence
+from typing import Dict, Optional, Sequence, Tuple
 
 from swh.model.model import Person, Revision, RevisionType, TimestampWithTimezone
 
@@ -41,7 +41,7 @@
 
 
 def build_swh_revision(
-    rev: int, commit: Dict, repo_uuid: str, dir_id: bytes, parents: Sequence[bytes]
+    rev: int, commit: Dict, repo_uuid: bytes, dir_id: bytes, parents: Sequence[bytes]
 ) -> Revision:
     """Given a svn revision, build a swh revision.
 
@@ -63,12 +63,10 @@
     msg = commit["message"]
     date = commit["author_date"]
 
-    metadata: Dict[str, Any] = {
-        "extra_headers": [
-            ["svn_repo_uuid", repo_uuid],
-            ["svn_revision", str(rev).encode("utf-8")],
-        ]
-    }
+    extra_headers: Tuple[Tuple[bytes, bytes], ...] = (
+        (b"svn_repo_uuid", repo_uuid),
+        (b"svn_revision", str(rev).encode()),
+    )
 
     return Revision(
         type=RevisionType.SUBVERSION,
@@ -79,6 +77,6 @@
         author=author,
         committer=author,
         synthetic=True,
-        metadata=metadata,
+        extra_headers=extra_headers,
         parents=tuple(parents),
     )
diff --git a/swh/loader/svn/loader.py b/swh/loader/svn/loader.py
--- a/swh/loader/svn/loader.py
+++ b/swh/loader/svn/loader.py
@@ -276,10 +276,10 @@
             return previous_swh_revision
         if partial_swh_revision and previous_swh_revision:
             # will determine from which to start from
-            extra_headers1 = dict(partial_swh_revision["metadata"]["extra_headers"])
-            extra_headers2 = dict(previous_swh_revision["metadata"]["extra_headers"])
-            rev_start1 = int(extra_headers1["svn_revision"])
-            rev_start2 = int(extra_headers2["svn_revision"])
+            extra_headers1 = dict(partial_swh_revision["extra_headers"])
+            extra_headers2 = dict(previous_swh_revision["extra_headers"])
+            rev_start1 = int(extra_headers1[b"svn_revision"])
+            rev_start2 = int(extra_headers2[b"svn_revision"])
             if rev_start1 <= rev_start2:
                 return previous_swh_revision
             return partial_swh_revision
@@ -326,8 +326,8 @@
             )
 
             if swh_rev:  # Yes, we know a previous revision. Try and update it.
-                extra_headers = dict(swh_rev["metadata"]["extra_headers"])
-                revision_start = int(extra_headers["svn_revision"])
+                extra_headers = dict(swh_rev["extra_headers"])
+                revision_start = int(extra_headers[b"svn_revision"])
                 revision_parents = {
                     revision_start: swh_rev["parents"],
                 }
@@ -682,8 +682,8 @@
         try:
             origin = self.storage.origin_get({"url": svn_url})
             last_swh_rev = self.swh_latest_snapshot_revision(origin["url"])["revision"]
-            last_swh_rev_headers = dict(last_swh_rev["metadata"]["extra_headers"])
-            last_loaded_svn_rev = int(last_swh_rev_headers["svn_revision"])
+            last_swh_rev_headers = dict(last_swh_rev["extra_headers"])
+            last_loaded_svn_rev = int(last_swh_rev_headers[b"svn_revision"])
         except Exception:
             pass
         return last_loaded_svn_rev
diff --git a/swh/loader/svn/tests/test_converters.py b/swh/loader/svn/tests/test_converters.py
--- a/swh/loader/svn/tests/test_converters.py
+++ b/swh/loader/svn/tests/test_converters.py
@@ -83,9 +83,7 @@
                 "fullname": b"theo <theo@uuid>",
             },
             "synthetic": True,
-            "metadata": {
-                "extra_headers": [["svn_repo_uuid", b"uuid"], ["svn_revision", b"10"],]
-            },
+            "extra_headers": ((b"svn_repo_uuid", b"uuid"), (b"svn_revision", b"10"),),
             "parents": (),
         }
     )