diff --git a/src/routes/txs/hash/required-signers.ts b/src/routes/txs/hash/required-signers.ts
index 1b9da4ee..97fbe888 100644
--- a/src/routes/txs/hash/required-signers.ts
+++ b/src/routes/txs/hash/required-signers.ts
@@ -6,6 +6,7 @@ import { SQLQuery } from '../../../sql/index.js';
 import * as QueryTypes from '../../../types/queries/tx.js';
 import * as ResponseTypes from '../../../types/responses/tx.js';
 import { getDbSync } from '../../../utils/database.js';
+import { handle404 } from '@blockfrost/blockfrost-utils/lib/fastify.js';
 
 async function route(fastify: FastifyInstance) {
   fastify.route({
@@ -16,6 +17,15 @@ async function route(fastify: FastifyInstance) {
       const clientDbSync = await getDbSync(fastify);
 
       try {
+        const query404 = await clientDbSync.query<QueryTypes.ResultFound>(SQLQuery.get('txs_404'), [
+          request.params.hash,
+        ]);
+
+        if (query404.rows.length === 0) {
+          clientDbSync.release();
+          return handle404(reply);
+        }
+
         const { rows }: { rows: ResponseTypes.TxWitnesses } =
           await clientDbSync.query<QueryTypes.TxWitnesses>(SQLQuery.get('txs_hash_wits'), [
             request.params.hash,