diff --git a/rattail_corepos/importing/corepos/db.py b/rattail_corepos/importing/corepos/db.py
index 924f493..88673e7 100644
--- a/rattail_corepos/importing/corepos/db.py
+++ b/rattail_corepos/importing/corepos/db.py
@@ -258,8 +258,11 @@ class MemberEquityPaymentImporter(FromCOREPOS, corepos_importing.model.MemberEqu
     Imports equity payment data from CORE-POS
     """
     host_model_class = coretrans.StockPurchase
-    # TODO: this is composite key for StockPurchase, but may need to change?
-    key = ('member_uuid', 'received', 'transaction_identifier')
+    key = ('corepos_card_number',
+           'corepos_transaction_number',
+           'corepos_transaction_id',
+           'corepos_department_number',
+           'corepos_datetime')
     supported_fields = [
         'member_uuid',
         'amount',