diff --git a/swh/lister/nixguix/lister.py b/swh/lister/nixguix/lister.py
--- a/swh/lister/nixguix/lister.py
+++ b/swh/lister/nixguix/lister.py
@@ -59,7 +59,9 @@
     """Either 'tar' or 'file' """
     fallback_urls: List[str]
     """List of urls to retrieve tarball artifact if canonical url no longer works."""
-    checksums: Dict[str, str]
+    is_integrity_about_artifact: bool
+    """Whether integrity field is about the artifact or the uncompressed directory"""
+    checksums: Optional[Dict[str, str]] = None
     """Integrity hash converted into a checksum dict."""
 
 
@@ -297,7 +299,7 @@
                 for url in origin_urls:
                     urlparsed = urlparse(url)
                     if urlparsed.scheme == "":
-                        logger.warning("Missing scheme for <%s>, fallback to http", url)
+                        logger.warning("Missing scheme for <%s>: fallback to http", url)
                         fixed_url = f"http://{url}"
                     else:
                         fixed_url = url
@@ -349,11 +351,23 @@
                     chksum_algo: base64.decodebytes(chksum_b64.encode()).hex()
                 }
 
+                # The 'outputHashMode' attribute determines how the hash is computed. It
+                # must be one of the following two values:
+                # - "flat": (default) The output must be a non-executable regular file.
+                #     If it isn’t, the build fails. The hash is simply computed over the
+                #     contents of that file (so it’s equal to what Unix commands like
+                #     `sha256sum` or `sha1sum` produce).
+                # - "recursive": The hash is computed over the NAR archive dump of the
+                #       output (i.e., the result of `nix-store --dump`). In this case,
+                #       the output can be anything, including a directory tree.
+                outputHashMode = artifact.get("outputHashMode", "flat")
+
                 logger.debug("%s: %s", "dir" if is_tar else "cnt", origin)
                 yield ArtifactType.ARTIFACT, Artifact(
                     origin=origin,
                     fallback_urls=fallback_urls,
                     checksums=checksums,
+                    is_integrity_about_artifact=outputHashMode == "flat",
                     visit_type="directory" if is_tar else "content",
                 )
             else:
@@ -376,12 +390,15 @@
     def artifact_to_listed_origin(self, artifact: Artifact) -> Iterator[ListedOrigin]:
         """Given an artifact (tarball, file), yield one ListedOrigin."""
         assert self.lister_obj.id is not None
+        key_checksum = (
+            "checksums" if artifact.is_integrity_about_artifact else "nar_checksums"
+        )
         yield ListedOrigin(
             lister_id=self.lister_obj.id,
             url=artifact.origin,
             visit_type=artifact.visit_type,
             extra_loader_arguments={
-                "checksums": artifact.checksums,
+                key_checksum: artifact.checksums,
                 "fallback_urls": artifact.fallback_urls,
             },
         )
diff --git a/swh/lister/nixguix/tests/data/nixpkgs-swh_sources.json b/swh/lister/nixguix/tests/data/nixpkgs-swh_sources.json
--- a/swh/lister/nixguix/tests/data/nixpkgs-swh_sources.json
+++ b/swh/lister/nixguix/tests/data/nixpkgs-swh_sources.json
@@ -38,6 +38,7 @@
     },
     {
       "type": "url",
+      "outputHashMode": "flat",
       "urls": [
         "http://downloads.sourceforge.net/project/nmon/lmon16n.c",
         "http://ufpr.dl.sourceforge.net/project/nmon/lmon16n.c",
@@ -45,6 +46,17 @@
       ],
       "integrity": "sha256-wAEswtkl3ulAw3zq4perrGS6Wlww5XXnQYsEAoYT9fI="
     },
+    {
+      "outputHash": "0s7p9swjqjsqddylmgid6cv263ggq7pmb734z4k84yfcrgb6kg4g",
+      "outputHashAlgo": "sha256",
+      "outputHashMode": "recursive",
+      "type": "url",
+      "urls": [
+        "https://github.com/kandu/trie/archive/1.0.0.tar.gz"
+      ],
+      "integrity": "sha256-j7xp1svMeYIm+WScVe/B7w0jNjMtvkp9a1hLLLlO92g=",
+      "inferredFetcher": "fetchzip"
+    },
     {
       "type": "git",
       "git_url": "https://example.org/pali/0xffff",