diff --git a/merch.sql b/merch.sql
index c5f363f..2a93555 100644
--- a/merch.sql
+++ b/merch.sql
@@ -51,4 +51,4 @@ CREATE TABLE merch_extra_data (
 
 );
 
-CREATE INDEX idx_merch_extra_data_merch_id ON merch_extra_data(merch_id);
\ No newline at end of file
+CREATE UNIQUE INDEX idx_merch_extra_data_merch_origin_id ON merch_extra_data (merch_id, origin_id);
\ No newline at end of file