diff --git a/java/src/main/java/org/softwareheritage/graph/utils/ListOriginContributors.java b/java/src/main/java/org/softwareheritage/graph/utils/ListOriginContributors.java
--- a/java/src/main/java/org/softwareheritage/graph/utils/ListOriginContributors.java
+++ b/java/src/main/java/org/softwareheritage/graph/utils/ListOriginContributors.java
@@ -5,7 +5,7 @@
  * See top-level LICENSE file for more information
  */
 
-/* For each origin and each person, outputs a line "origin_swhid,person_id",
+/* For each origin and each person, outputs a line "origin_id,person_id",
  * if that person contributed to the origin.
  *
  * This takes the output of TopoSort on stdin.
@@ -60,7 +60,7 @@
          */
         HashMap<Long, Long> pendingSuccessors = new HashMap<>();
 
-        System.out.println("origin_SWHID,person_id");
+        System.out.println("origin_id,person_id");
         while (stdin.hasNextLine()) {
             String cells[] = stdin.nextLine().strip().split(",", -1);
             SWHID nodeSWHID = new SWHID(cells[0]);
@@ -135,7 +135,7 @@
 
             if (nodeSWHID.getType() == SwhType.ORI) {
                 nodeContributors.forEach((contributorId) -> {
-                    System.out.format("%s,%d\n", nodeSWHID.toString(), contributorId);
+                    System.out.format("%d,%d\n", nodeId, contributorId);
                 });
             }
 
diff --git a/swh/graph/luigi/origin_contributors.py b/swh/graph/luigi/origin_contributors.py
--- a/swh/graph/luigi/origin_contributors.py
+++ b/swh/graph/luigi/origin_contributors.py
@@ -177,15 +177,15 @@
         with pyzstd.open(tmp_output_path, "wt") as output_fd:
             csv_writer = csv.writer(output_fd, lineterminator="\n")
             # write header
-            csv_writer.writerow(("origin_SWHID", "person_base64", "person_escaped"))
+            csv_writer.writerow(("origin_id", "person_base64", "person_escaped"))
 
             # Open input for reads as CSV
             with pyzstd.open(self.origin_contributors_path, "rt") as input_fd:
                 # TODO: remove that cast once we dropped Python 3.7 support
                 csv_reader = csv.reader(cast(Iterable[str], input_fd))
                 header = next(csv_reader)
-                assert header == ["origin_SWHID", "person_id"], header
-                for (origin_swhid, person_id) in csv_reader:
+                assert header == ["origin_id", "person_id"], header
+                for (origin_id, person_id) in csv_reader:
                     if person_id == "null":
                         # FIXME: workaround for a bug in contribution graphs generated
                         # before 2022-12-01. Those were only used in tests and never
@@ -194,6 +194,6 @@
                         continue
                     (name, escaped_name) = person_id_to_names[int(person_id)]
                     base64_name = base64.b64encode(name).decode("ascii")
-                    csv_writer.writerow((origin_swhid, base64_name, escaped_name))
+                    csv_writer.writerow((origin_id, base64_name, escaped_name))
 
         tmp_output_path.replace(self.deanonymized_origin_contributors_path)
diff --git a/swh/graph/tests/test_origin_contributors.py b/swh/graph/tests/test_origin_contributors.py
--- a/swh/graph/tests/test_origin_contributors.py
+++ b/swh/graph/tests/test_origin_contributors.py
@@ -29,12 +29,12 @@
 # FIXME: do not hardcode ids here; they should be dynamically loaded
 # from the test graph
 ORIGIN_CONTRIBUTORS = """\
-origin_SWHID,person_id
-swh:1:ori:83404f995118bd25774f4ac14422a8f175e7a054,0
-swh:1:ori:83404f995118bd25774f4ac14422a8f175e7a054,2
-swh:1:ori:8f50d3f60eae370ddbf85c86219c55108a350165,0
-swh:1:ori:8f50d3f60eae370ddbf85c86219c55108a350165,1
-swh:1:ori:8f50d3f60eae370ddbf85c86219c55108a350165,2
+origin_id,person_id
+2,0
+2,2
+0,0
+0,1
+0,2
 """
 
 DEANONYMIZATION_TABLE = """\
@@ -51,12 +51,12 @@
 """
 
 DEANONYMIZED_ORIGIN_CONTRIBUTORS = """\
-origin_SWHID,person_base64,person_escaped
-swh:1:ori:83404f995118bd25774f4ac14422a8f175e7a054,SmFuZSBEb2UgPGpkb2VAZXhhbXBsZS5jb20+,Jane Doe <jdoe@example.com>
-swh:1:ori:83404f995118bd25774f4ac14422a8f175e7a054,Sm9obiBEb2UgPGpkb2VAZXhhbXBsZS5vcmc+,John Doe <jdoe@example.org>
-swh:1:ori:8f50d3f60eae370ddbf85c86219c55108a350165,SmFuZSBEb2UgPGpkb2VAZXhhbXBsZS5jb20+,Jane Doe <jdoe@example.com>
-swh:1:ori:8f50d3f60eae370ddbf85c86219c55108a350165,SmFuZSBEb2UgPGpkb2VAZXhhbXBsZS5uZXQ+,Jane Doe <jdoe@example.net>
-swh:1:ori:8f50d3f60eae370ddbf85c86219c55108a350165,Sm9obiBEb2UgPGpkb2VAZXhhbXBsZS5vcmc+,John Doe <jdoe@example.org>
+origin_id,person_base64,person_escaped
+2,SmFuZSBEb2UgPGpkb2VAZXhhbXBsZS5jb20+,Jane Doe <jdoe@example.com>
+2,Sm9obiBEb2UgPGpkb2VAZXhhbXBsZS5vcmc+,John Doe <jdoe@example.org>
+0,SmFuZSBEb2UgPGpkb2VAZXhhbXBsZS5jb20+,Jane Doe <jdoe@example.com>
+0,SmFuZSBEb2UgPGpkb2VAZXhhbXBsZS5uZXQ+,Jane Doe <jdoe@example.net>
+0,Sm9obiBEb2UgPGpkb2VAZXhhbXBsZS5vcmc+,John Doe <jdoe@example.org>
 """  # noqa