diff --git a/index.js b/index.js
index 842adda..fafbaee 100644
--- a/index.js
+++ b/index.js
@@ -311,7 +311,16 @@ Syscoin.prototype.fetchAndSanitizeUTXOs = async function (utxos, fromXpubOrAddre
       utxos = utils.sanitizeBlockbookUTXOs(fromXpubOrAddress, utxos, this.network, txOpts, assetMap, excludeZeroConf)
     }
   } else {
-    utxos = utils.sanitizeBlockbookUTXOs(fromXpubOrAddress, utxos, this.network, txOpts, assetMap, excludeZeroConf)
+    // Only sanitize if UTXOs are not already in sanitized format.
+    // Sanitized UTXOs have a .utxos array with BN values and camelCase txId fields.
+    // Re-sanitizing already-sanitized UTXOs causes txId to be lost because
+    // sanitizeBlockbookUTXOs reads utxo.txid (lowercase) which is undefined
+    // on already-sanitized objects, breaking PSBT construction for WIF signers.
+    const isAlreadySanitized = utxos && Array.isArray(utxos.utxos) && 
+      utxos.utxos.length > 0 && utxos.utxos[0].txId !== undefined
+    if (!isAlreadySanitized) {
+      utxos = utils.sanitizeBlockbookUTXOs(fromXpubOrAddress, utxos, this.network, txOpts, assetMap, excludeZeroConf)
+    }
   }
   return utxos
 }