diff --git a/packages/ton-to-cw/src/tx-processor.ts b/packages/ton-to-cw/src/tx-processor.ts
index b704192..b37b22b 100644
--- a/packages/ton-to-cw/src/tx-processor.ts
+++ b/packages/ton-to-cw/src/tx-processor.ts
@@ -84,9 +84,15 @@ export default class TonTxProcessor {
         (tx) => tx.tx.hash().toString("hex") === this.latestProcessedTxHash
       );
       if (indexOf === -1) {
+        const oldestTx = txs[txs.length - 1].tx;
+        if (!oldestTx.prevTransactionHash) {
+          this.logger.error(
+            "TonTxProcessor queryUnprocessedTransactions new offset hash is undefined"
+          );
+          continue;
+        }
         transactions.push(...txs);
         // increase offset and continue querying txs until we find our oldest transaction that we can remember
-        const oldestTx = txs[txs.length - 1].tx;
         offset = {
           hash: oldestTx.prevTransactionHash.toString(16),
           lt: oldestTx.prevTransactionLt.toString(10),