diff --git a/src/helpers.ts b/src/helpers.ts
index ceaed7524..525977193 100644
--- a/src/helpers.ts
+++ b/src/helpers.ts
@@ -520,7 +520,7 @@ export default class Helpers {
    * @param {object} reqOptions - The client optional configuration for this request.
    * @return {object} The possible operations to run with the datasource.
    */
-  bulk<TDocument = unknown> (options: BulkHelperOptions, reqOptions: TransportRequestOptions = {}): BulkHelper<TDocument> {
+  bulk<TDocument = unknown> (options: BulkHelperOptions<TDocument>, reqOptions: TransportRequestOptions = {}): BulkHelper<TDocument> {
     const client = this[kClient]
     const { serializer } = client
     if (this[kMetaHeader] !== null) {
@@ -790,6 +790,7 @@ export default class Helpers {
               status: 429,
               error: null,
               operation: serializer.deserialize(bulkBody[i]),
+              // @ts-expect-error
               document: operation !== 'delete'
                 ? serializer.deserialize(bulkBody[i + 1])
                 /* istanbul ignore next */
@@ -841,6 +842,7 @@ export default class Helpers {
                     status: responseItem.status,
                     error: responseItem.error ?? null,
                     operation: serializer.deserialize(bulkBody[indexSlice]),
+                    // @ts-expect-error
                     document: operation !== 'delete'
                       ? serializer.deserialize(bulkBody[indexSlice + 1])
                       : null,
diff --git a/test/unit/helpers/bulk.test.ts b/test/unit/helpers/bulk.test.ts
index d9bfcda6c..5a182009e 100644
--- a/test/unit/helpers/bulk.test.ts
+++ b/test/unit/helpers/bulk.test.ts
@@ -42,6 +42,11 @@ const dataset = [
   { user: 'tyrion', age: 39 }
 ]
 
+interface Document {
+  user: string
+  age: number
+}
+
 test('bulk index', t => {
   t.test('datasource as array', t => {
     t.test('Should perform a bulk request', async t => {
@@ -65,11 +70,12 @@ test('bulk index', t => {
         node: 'http://localhost:9200',
         Connection: MockConnection
       })
-      const result = await client.helpers.bulk({
+      const result = await client.helpers.bulk<Document>({
         datasource: dataset.slice(),
         flushBytes: 1,
         concurrency: 1,
         onDocument (doc) {
+          t.type(doc.user, 'string') // testing that doc is type of Document
           return {
             index: { _index: 'test' }
           }