diff --git a/atlas/templates/atlas/partials/casedetails_management_links.html b/atlas/templates/atlas/partials/casedetails_management_links.html
index 48776660..2c710e2a 100644
--- a/atlas/templates/atlas/partials/casedetails_management_links.html
+++ b/atlas/templates/atlas/partials/casedetails_management_links.html
@@ -18,7 +18,7 @@
         {% endif %}
 
         {% if casedetail.case.previous_case %}
-            <a class="btn btn-outline-secondary" href='{% url "atlas:collection_case_priors" casedetail.collection.pk casedetail.case.pk %}' title="Manage priors">
+            <a class="btn btn-outline-secondary" href='{% url "atlas:collection_case_priors_legacy" casedetail.collection.pk casedetail.case.pk %}' title="Manage priors">
                 <i class="bi bi-link-45deg"></i>
             </a>
         {% endif %}
diff --git a/atlas/views.py b/atlas/views.py
index 6d2b0b11..21316d19 100755
--- a/atlas/views.py
+++ b/atlas/views.py
@@ -2834,22 +2834,13 @@ def redirect_collection_case_view_take_user_answers_by_id(request, pk, case_id):
 
 
 @user_is_collection_author_or_atlas_editor
-def collection_case_priors(request, exam_id, case_id):
-    # Support either case_number (index) or case_id (case PK) in the URL/kwargs.
-    # Backwards compatibility: callers may pass case_id; prefer case_number when present.
-    casedetail = None
-    collection = None
-    # Try treating the parameter as a case PK first, falling back to case index.
+def collection_case_priors(request, exam_id, case_number):
+    collection = get_object_or_404(CaseCollection, pk=exam_id)
     try:
-        casedetail = CaseDetail.objects.get(case=case_id, collection=exam_id)
-        collection = casedetail.collection
+        case_obj = collection.get_case_by_index(case_number)
+        casedetail = CaseDetail.objects.get(case=case_obj, collection=collection)
     except Exception:
-        collection = get_object_or_404(CaseCollection, pk=exam_id)
-        try:
-            case_obj = collection.get_case_by_index(int(case_id))
-            casedetail = CaseDetail.objects.get(case=case_obj, collection=collection)
-        except Exception:
-            raise Http404("Case not found in collection")
+        raise Http404("Case not found in collection")
 
     if request.htmx:
         # Ensure we can render the updated single-card partial and return it so HTMX