diff --git a/swh/loader/package/npm.py b/swh/loader/package/npm.py
--- a/swh/loader/package/npm.py
+++ b/swh/loader/package/npm.py
@@ -73,12 +73,7 @@
     def resolve_revision_from(
             self, known_artifacts: Dict, artifact_metadata: Dict) \
             -> Optional[bytes]:
-        shasum = artifact_metadata['dist']['shasum']
-        for rev_id, known_artifact in known_artifacts.items():
-            original_artifact = known_artifact['original_artifact'][0]
-            if shasum == original_artifact['checksums']['sha1']:
-                return rev_id
-        return None
+        return artifact_to_revision_id(known_artifacts, artifact_metadata)
 
     def build_revision(
             self, a_metadata: Dict, uncompressed_path: str) -> Dict:
@@ -119,6 +114,50 @@
         }
 
 
+def artifact_to_revision_id(
+        known_artifacts: Dict, artifact_metadata: Dict) -> Optional[bytes]:
+    """Given metadata artifact, solves the associated revision id.
+
+    The following code allows to deal with 2 metadata formats:
+
+    - old format sample:
+
+        {
+            'package_source': {
+                'sha1': '05181c12cd8c22035dd31155656826b85745da37',
+            }
+        }
+
+    - new format sample:
+
+        {
+            'original_artifact': [{
+                'checksums': {
+                    'sha256': "6975816f2c5ad4046acc676ba112f2fff945b01522d63948531f11f11e0892ec",  # noqa
+                    ...
+                },
+            }],
+            ...
+        }
+
+    """
+    shasum = artifact_metadata['dist']['shasum']
+    for rev_id, known_artifact in known_artifacts.items():
+        known_original_artifact = known_artifact.get('original_artifact')
+        if not known_original_artifact:
+            # previous loader-npm version kept original artifact elsewhere
+            known_original_artifact = known_artifact.get('package_source')
+            if not known_original_artifact:
+                continue
+            original_hash = known_original_artifact['sha1']
+        else:
+            assert isinstance(known_original_artifact, list)
+            original_hash = known_original_artifact[0]['checksums']['sha1']
+        if shasum == original_hash:
+            return rev_id
+    return None
+
+
 def parse_npm_package_author(author_str):
     """
     Parse npm package author string.
diff --git a/swh/loader/package/tests/test_npm.py b/swh/loader/package/tests/test_npm.py
--- a/swh/loader/package/tests/test_npm.py
+++ b/swh/loader/package/tests/test_npm.py
@@ -11,7 +11,8 @@
 from swh.model.hashutil import hash_to_bytes
 
 from swh.loader.package.npm import (
-    parse_npm_package_author, extract_npm_package_author
+    parse_npm_package_author, extract_npm_package_author,
+    artifact_to_revision_id
 )
 from swh.loader.package.tests.common import (
     check_snapshot, check_metadata_paths, get_stats
@@ -582,3 +583,79 @@
         },
     }
     check_snapshot(expected_snapshot, loader.storage)
+
+
+def test_npm_artifact_to_revision_id_none():
+    """Current loader version should stop soon if nothing can be found
+
+    """
+    artifact_metadata = {
+        'dist': {
+            'shasum': '05181c12cd8c22035dd31155656826b85745da37',
+        },
+    }
+
+    known_artifacts = {
+        'b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92': {},
+    }
+
+    assert artifact_to_revision_id(known_artifacts, artifact_metadata) is None
+
+
+def test_npm_artifact_to_revision_id_old_loader_version():
+    """Current loader version should solve old metadata scheme
+
+    """
+    artifact_metadata = {
+        'dist': {
+            'shasum': '05181c12cd8c22035dd31155656826b85745da37',
+        }
+    }
+
+    known_artifacts = {
+        hash_to_bytes('b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92'): {
+            'package_source': {
+                'sha1': "something-wrong"
+            }
+        },
+        hash_to_bytes('845673bfe8cbd31b1eaf757745a964137e6f9116'): {
+            'package_source': {
+                'sha1': '05181c12cd8c22035dd31155656826b85745da37',
+            }
+        }
+
+    }
+
+    assert artifact_to_revision_id(known_artifacts, artifact_metadata) \
+        == hash_to_bytes('845673bfe8cbd31b1eaf757745a964137e6f9116')
+
+
+def test_npm_artifact_to_revision_id_current_loader_version():
+    """Current loader version should be able to solve current metadata scheme
+
+    """
+    artifact_metadata = {
+        'dist': {
+            'shasum': '05181c12cd8c22035dd31155656826b85745da37',
+        }
+    }
+
+    known_artifacts = {
+        hash_to_bytes('b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92'): {
+            'original_artifact': [{
+                'checksums': {
+                    'sha1': "05181c12cd8c22035dd31155656826b85745da37"
+                },
+            }],
+        },
+        hash_to_bytes('845673bfe8cbd31b1eaf757745a964137e6f9116'): {
+            'original_artifact': [{
+                'checksums': {
+                    'sha1': 'something-wrong'
+                },
+            }],
+        },
+    }
+
+    assert artifact_to_revision_id(known_artifacts, artifact_metadata) \
+        == hash_to_bytes('b11ebac8c9d0c9e5063a2df693a18e3aba4b2f92')