diff --git a/swh/loader/package/cpan/loader.py b/swh/loader/package/cpan/loader.py
--- a/swh/loader/package/cpan/loader.py
+++ b/swh/loader/package/cpan/loader.py
@@ -15,9 +15,11 @@
 from swh.loader.package.loader import (
     BasePackageInfo,
     PackageLoader,
+    PartialExtID,
     RawExtrinsicMetadataCore,
 )
 from swh.loader.package.utils import EMPTY_AUTHOR, Person, get_url_body, release_name
+from swh.model.hashutil import hash_to_bytes
 from swh.model.model import (
     MetadataAuthority,
     MetadataAuthorityType,
@@ -30,6 +32,9 @@
 
 logger = logging.getLogger(__name__)
 
+EXTID_TYPE = "cpan-archive-sha256"
+EXTID_VERSION = 0
+
 
 @attr.s
 class CpanPackageInfo(BasePackageInfo):
@@ -46,6 +51,9 @@
     author = attr.ib(type=Person)
     """Author"""
 
+    def extid(self) -> PartialExtID:
+        return (EXTID_TYPE, EXTID_VERSION, hash_to_bytes(self.checksums["sha256"]))
+
 
 class CpanLoader(PackageLoader[CpanPackageInfo]):
     visit_type = "cpan"
diff --git a/swh/loader/package/cpan/tests/test_cpan.py b/swh/loader/package/cpan/tests/test_cpan.py
--- a/swh/loader/package/cpan/tests/test_cpan.py
+++ b/swh/loader/package/cpan/tests/test_cpan.py
@@ -11,7 +11,7 @@
 import pytest
 
 from swh.loader.package import __version__
-from swh.loader.package.cpan.loader import CpanLoader
+from swh.loader.package.cpan.loader import EXTID_TYPE, EXTID_VERSION, CpanLoader
 from swh.loader.tests import assert_last_visit_matches, check_snapshot, get_stats
 from swh.model.hashutil import hash_to_bytes
 from swh.model.model import (
@@ -207,3 +207,20 @@
         ).results
         == expected_metadata
     )
+
+    extids = storage.extid_get_from_extid(
+        id_type=EXTID_TYPE,
+        ids=[
+            hash_to_bytes(artifact["checksums"]["sha256"])
+            for artifact in ORIGIN_ARTIFACTS
+        ],
+        version=EXTID_VERSION,
+    )
+
+    release_swhids = {
+        CoreSWHID(object_type=ObjectType.RELEASE, object_id=branch.target)
+        for branch in expected_snapshot.branches.values()
+        if branch.target_type == TargetType.RELEASE
+    }
+
+    assert {extid.target for extid in extids} == release_swhids