diff --git a/swh/loader/package/nixguix/loader.py b/swh/loader/package/nixguix/loader.py
--- a/swh/loader/package/nixguix/loader.py
+++ b/swh/loader/package/nixguix/loader.py
@@ -41,6 +41,10 @@
         s = retrieve_sources(url)
         self.sources = s['sources']
         self.provider_url = url
+
+        self._integrityByUrl = {s['url'][0]: s['integrity']
+                                for s in self.sources}
+
         # The revision used to create the sources.json file. For Nix,
         # this revision belongs to the github.com/nixos/nixpkgs
         # repository
@@ -49,24 +53,32 @@
     # Note: this could be renamed get_artifacts in the PackageLoader
     # base class.
     def get_versions(self):
+        """The first mirror of the mirror list is used as branch name in the
+        snapshot.
+
+        """
+        return self._integrityByUrl.keys()
+
+    # Note: this could be renamed get_artifact_info in the PackageLoader
+    # base class.
+    def get_package_info(self, url):
         # TODO: try all mirrors and not only the first one. A source
         # can be fetched from several urls, called mirrors. We
         # currently only use the first one, but if the first one
         # fails, we should try the second one and so on.
-        return [s['url'][0] for s in self.sources]
-
-    # Note: this could be renamed get_artifact_info in the PackageLoader
-    # base class.
-    def get_package_info(self, source):
-        # TODO: we need to provide the sha256 of the source also
-        yield source, {'url': source, 'raw': {'url': source}}
+        integrity = self._integrityByUrl[url]
+        yield url, {'url': url,
+                    'raw': {
+                        'url': url,
+                        'integrity': integrity}}
 
     def resolve_revision_from(
             self, known_artifacts: Dict, artifact_metadata: Dict) \
             -> Optional[bytes]:
+
         for rev_id, known_artifact in known_artifacts.items():
-            known_url = known_artifact['extrinsic']['raw']['url']
-            if artifact_metadata['url'] == known_url:
+            known_integrity = known_artifact['extrinsic']['raw']['integrity']
+            if artifact_metadata['integrity'] == known_integrity:
                 return rev_id
         return None
 
diff --git a/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources-EOFError.json b/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources-EOFError.json
--- a/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources-EOFError.json
+++ b/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources-EOFError.json
@@ -2,7 +2,8 @@
   "sources": [
     {
       "type": "url",
-      "url": [ "https://fail.com/truncated-archive.tgz" ]
+      "url": [ "https://fail.com/truncated-archive.tgz" ],
+      "integrity": "sha256-UB+RzIn63O0WxzqohYeWZRRzYCxyK7Kfhqi6WI0P8bE="
     }
  ],
     "version": 1,
diff --git a/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json b/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json
--- a/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json
+++ b/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json
@@ -2,11 +2,13 @@
   "sources": [
     {
       "type": "url",
-      "url": [ "https://github.com/owner-1/repository-1/revision-1.tgz" ]
+      "url": [ "https://github.com/owner-1/repository-1/revision-1.tgz" ],
+      "integrity": "sha256-3vm2Nt+O4zHf3Ovd/qsv1gKTEUwodX9FLxlrQdry0zs="
     },
     {
       "type": "url",
-      "url": [ "https://example.com/file.txt" ]
+      "url": [ "https://example.com/file.txt" ],
+      "integrity": "sha256-Q0copBCnj1b8G1iZw1k0NuYasMcx6QctleltspAgXlM="
     }
  ],
     "version": 1,
diff --git a/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json_visit1 b/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json_visit1
--- a/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json_visit1
+++ b/swh/loader/package/nixguix/tests/data/https_nix-community.github.io/nixpkgs-swh_sources.json_visit1
@@ -2,15 +2,18 @@
   "sources": [
     {
       "type": "url",
-      "url": [ "https://github.com/owner-1/repository-1/revision-1.tgz" ]
+      "url": [ "https://github.com/owner-1/repository-1/revision-1.tgz" ],
+      "integrity": "sha256-3vm2Nt+O4zHf3Ovd/qsv1gKTEUwodX9FLxlrQdry0zs="
     },
     {
       "type": "url",
-      "url": [ "https://github.com/owner-2/repository-1/revision-1.tgz" ]
+      "url": [ "https://github.com/owner-2/repository-1/revision-1.tgz" ],
+      "integrity": "sha256-+vRlzTcnhMlynJGGMuAgMnUGdjpSqGabhcQ/SlRplAE="
     },
     {
       "type": "url",
-      "url": [ "https://example.com/file.txt" ]
+      "url": [ "https://example.com/file.txt" ],
+      "integrity": "sha256-Q0copBCnj1b8G1iZw1k0NuYasMcx6QctleltspAgXlM="
     }
  ],
   "version": 1,
diff --git a/swh/loader/package/nixguix/tests/test_functional.py b/swh/loader/package/nixguix/tests/test_functional.py
--- a/swh/loader/package/nixguix/tests/test_functional.py
+++ b/swh/loader/package/nixguix/tests/test_functional.py
@@ -218,13 +218,17 @@
     loader = NixGuixLoader(sources_url)
 
     known_artifacts = {
-        'id1': {'extrinsic': {'raw': {'url': "url1"}}},
-        'id2': {'extrinsic': {'raw': {'url': "url2"}}}
+        'id1': {'extrinsic': {'raw': {
+            'url': "url1",
+            'integrity': 'integrity1'}}},
+        'id2': {'extrinsic': {'raw': {
+            'url': "url2",
+            'integrity': 'integrity2'}}},
         }
 
-    metadata = {'url': 'url1'}
+    metadata = {'url': 'url1', 'integrity': 'integrity1'}
     assert loader.resolve_revision_from(known_artifacts, metadata) == 'id1'
-    metadata = {'url': 'url3'}
+    metadata = {'url': 'url3', 'integrity': 'integrity3'}
     assert loader.resolve_revision_from(known_artifacts, metadata) == None # noqa