diff --git a/src/db.rs b/src/db.rs
index 269e9b6..fe96728 100644
--- a/src/db.rs
+++ b/src/db.rs
@@ -250,6 +250,7 @@ impl Database {
             r#"
             INSERT INTO tx_hashes (tx_id, tx_hash, max_fee_per_gas, max_priority_fee_per_gas)
             VALUES ($1, $2, $3, $4)
+            ON CONFLICT (tx_hash) DO NOTHING
             "#,
         )
         .bind(tx_id)