diff --git a/swh/loader/mercurial/loader.py b/swh/loader/mercurial/loader.py
--- a/swh/loader/mercurial/loader.py
+++ b/swh/loader/mercurial/loader.py
@@ -41,12 +41,12 @@
     MultiHash,
     hash_to_bytehex,
     hash_to_bytes,
-    hash_to_hex,
 )
 from swh.model.model import (
     BaseContent,
     Content,
     Directory,
+    ExtID,
     ObjectType,
     Origin,
     Person,
@@ -75,6 +75,8 @@
 
 HEAD_POINTER_NAME = b"tip"
 
+EXTID_TYPE = "hg-nodeid"
+
 
 class CommandErrorWrapper(Exception):
     """This exception is raised in place of a 'CommandError'
@@ -256,6 +258,7 @@
         self.releases = {}
         self.node_2_rev = {}
         self.heads = {}
+        self.extids = []
 
         directory = self.directory
 
@@ -531,7 +534,6 @@
                 type=RevisionType.MERCURIAL,
                 directory=directory_id,
                 message=commit["message"],
-                metadata={"node": hash_to_hex(header["node"]),},
                 extra_headers=tuple(extra_headers),
                 synthetic=False,
                 parents=tuple(parents),
@@ -540,6 +542,15 @@
             self.node_2_rev[header["node"]] = revision.id
             revisions[revision.id] = revision
 
+            revision_swhid = identifiers.CoreSWHID(
+                object_type=identifiers.ObjectType.REVISION, object_id=revision.id,
+            )
+            self.extids.append(
+                ExtID(
+                    extid_type=EXTID_TYPE, extid=header["node"], target=revision_swhid
+                )
+            )
+
         # Converts heads to use swh ids
         self.heads = {
             branch_name: (pointer_nature, self.node_2_rev[node_id])
@@ -618,6 +629,10 @@
         self.snapshot = Snapshot(branches=branches)
         return self.snapshot
 
+    def store_data(self) -> None:
+        super().store_data()
+        self.storage.extid_add(self.extids)
+
     def get_fetch_history_result(self):
         """Return the data to store in fetch_history."""
         return {
diff --git a/swh/loader/mercurial/tests/test_loader.py b/swh/loader/mercurial/tests/test_loader.py
--- a/swh/loader/mercurial/tests/test_loader.py
+++ b/swh/loader/mercurial/tests/test_loader.py
@@ -19,7 +19,8 @@
     get_stats,
     prepare_repository_from_archive,
 )
-from swh.model.hashutil import hash_to_bytes
+from swh.model.hashutil import hash_to_bytes, hash_to_hex
+from swh.model.identifiers import ObjectType
 from swh.model.model import RevisionType, Snapshot, SnapshotBranch, TargetType
 from swh.storage.algos.snapshot import snapshot_get_latest
 
@@ -307,7 +308,11 @@
     hg_changesets = set()
     transplant_sources = set()
     for rev in swh_storage.revision_log(revisions):
-        hg_changesets.add(rev["metadata"]["node"])
+        extids = list(
+            loader.storage.extid_get_from_target(ObjectType.REVISION, [rev["id"]])
+        )
+        assert len(extids) == 1
+        hg_changesets.add(hash_to_hex(extids[0].extid))
         for k, v in rev["extra_headers"]:
             if k == b"transplant_source":
                 transplant_sources.add(v.decode("ascii"))