diff --git a/repo-scripts/upgrade-reference b/repo-scripts/upgrade-reference
index 8f47555bda72b21f95408b538851fb843577285d_cmVwby1zY3JpcHRzL3VwZ3JhZGUtcmVmZXJlbmNl..5b587afd50bc04af718320cd9963cd27044cc50f_cmVwby1zY3JpcHRzL3VwZ3JhZGUtcmVmZXJlbmNl 100755
--- a/repo-scripts/upgrade-reference
+++ b/repo-scripts/upgrade-reference
@@ -72,9 +72,9 @@
     new_benchrepo = benchrepo_data.copy()
     new_benchrepo["reference-repo"]["format-info"] = format_data
 
-    # Update the repo hash manually because we need the format info to compute
-    # the hash
-    new_benchrepo["reference-repo"]["repo-hash"] = reference_id
+    # drop legacy "repo-hash" attribute
+    new_benchrepo["reference-repo"].pop("repo-hash", None)
+    # Update the associated repo-prefix
     new_benchrepo["reference-repo"]["repo-prefix"] = repo_prefix
 
     # And write it
diff --git a/tests/test-upgrade-reference.t b/tests/test-upgrade-reference.t
index 8f47555bda72b21f95408b538851fb843577285d_dGVzdHMvdGVzdC11cGdyYWRlLXJlZmVyZW5jZS50..5b587afd50bc04af718320cd9963cd27044cc50f_dGVzdHMvdGVzdC11cGdyYWRlLXJlZmVyZW5jZS50 100644
--- a/tests/test-upgrade-reference.t
+++ b/tests/test-upgrade-reference.t
@@ -108,7 +108,6 @@
       plain-cl-delta: true
       sparserevlog: true
     id: my-source-repo
-    repo-hash: 39241d24
     repo-prefix: my-source-repo-39241d24
     source: some-dir/my-source-repo