diff --git a/InvenTree/order/serializers.py b/InvenTree/order/serializers.py
index 2f87727ced..e9838f3347 100644
--- a/InvenTree/order/serializers.py
+++ b/InvenTree/order/serializers.py
@@ -7,7 +7,7 @@ from __future__ import unicode_literals
 
 from rest_framework import serializers
 
-from django.db.models import Count
+from sql_util.utils import SubqueryCount
 
 from InvenTree.serializers import InvenTreeModelSerializer
 from InvenTree.serializers import InvenTreeAttachmentSerializerField
@@ -39,10 +39,12 @@ class POSerializer(InvenTreeModelSerializer):
         Add extra information to the queryset
         """
 
-        return queryset.annotate(
-            line_items=Count('lines'),
+        queryset = queryset.annotate(
+            line_items=SubqueryCount('lines')
         )
 
+        return queryset
+
     supplier_detail = CompanyBriefSerializer(source='supplier', many=False, read_only=True)
     
     line_items = serializers.IntegerField(read_only=True)
@@ -147,10 +149,12 @@ class SalesOrderSerializer(InvenTreeModelSerializer):
         Add extra information to the queryset
         """
 
-        return queryset.annotate(
-            line_items=Count('lines'),
+        queryset = queryset.annotate(
+            line_items=SubqueryCount('lines')
         )
 
+        return queryset
+
     customer_detail = CompanyBriefSerializer(source='customer', many=False, read_only=True)
 
     line_items = serializers.IntegerField(read_only=True)