diff --git a/db/migrations/00040_associate_receipts_with_blocks.sql b/db/migrations/00040_associate_receipts_with_blocks.sql
index dea130fb..889772ff 100644
--- a/db/migrations/00040_associate_receipts_with_blocks.sql
+++ b/db/migrations/00040_associate_receipts_with_blocks.sql
@@ -24,6 +24,8 @@ ALTER TABLE receipts
 ALTER TABLE receipts
   ADD COLUMN transaction_id INT;
 
+CREATE INDEX transaction_id_index ON receipts (transaction_id);
+
 UPDATE receipts
   SET transaction_id = (
     SELECT id FROM transactions WHERE transactions.hash = receipts.tx_hash