diff --git a/django_etebase/models.py b/django_etebase/models.py
index d1095fb..af4d022 100644
--- a/django_etebase/models.py
+++ b/django_etebase/models.py
@@ -31,6 +31,11 @@ from .exceptions import EtebaseValidationError
 UidValidator = RegexValidator(regex=r"^[a-zA-Z0-9\-_]{20,}$", message="Not a valid UID")
 
 
+def stoken_annotation_builder(stoken_id_fields):
+    aggr_fields = [Coalesce(Max(field), V(0)) for field in stoken_id_fields]
+    return Greatest(*aggr_fields) if len(aggr_fields) > 1 else aggr_fields[0]
+
+
 class CollectionType(models.Model):
     owner = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
     uid = models.BinaryField(editable=True, blank=False, null=False, db_index=True, unique=True)
@@ -40,7 +45,7 @@ class Collection(models.Model):
     main_item = models.OneToOneField("CollectionItem", related_name="parent", null=True, on_delete=models.SET_NULL)
     owner = models.ForeignKey(settings.AUTH_USER_MODEL, on_delete=models.CASCADE)
 
-    stoken_id_fields = ["items__revisions__stoken", "members__stoken"]
+    stoken_annotation = stoken_annotation_builder(["items__revisions__stoken", "members__stoken"])
 
     def __str__(self):
         return self.uid
@@ -59,11 +64,9 @@ class Collection(models.Model):
 
     @cached_property
     def stoken(self):
-        aggr_fields = [Coalesce(Max(field), V(0)) for field in self.stoken_id_fields]
-        max_stoken = Greatest(*aggr_fields) if len(aggr_fields) > 1 else aggr_fields[0]
         stoken_id = (
             self.__class__.objects.filter(main_item=self.main_item)
-            .annotate(max_stoken=max_stoken)
+            .annotate(max_stoken=self.stoken_annotation)
             .values("max_stoken")
             .first()["max_stoken"]
         )
@@ -94,6 +97,8 @@ class CollectionItem(models.Model):
     version = models.PositiveSmallIntegerField()
     encryptionKey = models.BinaryField(editable=True, blank=False, null=True)
 
+    stoken_annotation = stoken_annotation_builder(["revisions__stoken"])
+
     class Meta:
         unique_together = ("uid", "collection")
 
@@ -191,6 +196,8 @@ class CollectionMember(models.Model):
         default=AccessLevels.READ_ONLY,
     )
 
+    stoken_annotation = stoken_annotation_builder(["stoken"])
+
     class Meta:
         unique_together = ("user", "collection")
 
diff --git a/django_etebase/views.py b/django_etebase/views.py
index 8c05948..d1266c6 100644
--- a/django_etebase/views.py
+++ b/django_etebase/views.py
@@ -18,8 +18,7 @@ from django.conf import settings
 from django.contrib.auth import get_user_model, user_logged_in, user_logged_out
 from django.core.exceptions import PermissionDenied
 from django.db import transaction, IntegrityError
-from django.db.models import Max, Value as V, Q
-from django.db.models.functions import Coalesce, Greatest
+from django.db.models import Q
 from django.http import HttpResponseBadRequest, HttpResponse, Http404
 from django.shortcuts import get_object_or_404
 
@@ -94,7 +93,7 @@ class BaseViewSet(viewsets.ModelViewSet):
     permission_classes = tuple(app_settings.API_PERMISSIONS)
     renderer_classes = [JSONRenderer, MessagePackRenderer] + ([BrowsableAPIRenderer] if settings.DEBUG else [])
     parser_classes = [JSONParser, MessagePackParser, FormParser, MultiPartParser]
-    stoken_id_fields = None
+    stoken_annotation = None
 
     def get_serializer_class(self):
         serializer_class = self.serializer_class
@@ -125,9 +124,7 @@ class BaseViewSet(viewsets.ModelViewSet):
     def filter_by_stoken(self, request, queryset):
         stoken_rev = self.get_stoken_obj(request)
 
-        aggr_fields = [Coalesce(Max(field), V(0)) for field in self.stoken_id_fields]
-        max_stoken = Greatest(*aggr_fields) if len(aggr_fields) > 1 else aggr_fields[0]
-        queryset = queryset.annotate(max_stoken=max_stoken).order_by("max_stoken")
+        queryset = queryset.annotate(max_stoken=self.stoken_annotation).order_by("max_stoken")
 
         if stoken_rev is not None:
             queryset = queryset.filter(max_stoken__gt=stoken_rev.id)
@@ -179,7 +176,7 @@ class CollectionViewSet(BaseViewSet):
     serializer_class = CollectionSerializer
     lookup_field = "main_item__uid"
     lookup_url_kwarg = "uid"
-    stoken_id_fields = ["items__revisions__stoken__id", "members__stoken__id"]
+    stoken_annotation = Collection.stoken_annotation
 
     def get_queryset(self, queryset=None):
         if queryset is None:
@@ -262,7 +259,7 @@ class CollectionItemViewSet(BaseViewSet):
     queryset = CollectionItem.objects.all()
     serializer_class = CollectionItemSerializer
     lookup_field = "uid"
-    stoken_id_fields = ["revisions__stoken__id"]
+    stoken_annotation = CollectionItem.stoken_annotation
 
     def get_queryset(self):
         collection_uid = self.kwargs["collection_uid"]
@@ -482,7 +479,7 @@ class CollectionMemberViewSet(BaseViewSet):
     serializer_class = CollectionMemberSerializer
     lookup_field = f"user__{User.USERNAME_FIELD}__iexact"
     lookup_url_kwarg = "username"
-    stoken_id_fields = ["stoken__id"]
+    stoken_annotation = CollectionMember.stoken_annotation
 
     # FIXME: need to make sure that there's always an admin, and maybe also don't let an owner remove adm access
     # (if we want to transfer, we need to do that specifically)