diff --git a/README.md b/README.md
index 2763e74..7bd0307 100644
--- a/README.md
+++ b/README.md
@@ -245,10 +245,16 @@ var batch = {
   }]
 }
 
-client.updateBatchSubscribers(batch, function (errors, responses, bodies) {
-  // Do stuff
-  }
-)
+client.updateBatchSubscribers(batch, (errors, responses, bodies) => {
+    // Do stuff...
+    if (errors) {
+      console.error('Some requests failed:', errors);
+    } else {
+      console.log('All requests succeeded');
+    }
+    console.log('Responses:', responses);
+    console.log('Bodies:', bodies);
+  });
 ```
 
 ### Sending a batch of events
diff --git a/lib/subscribers.js b/lib/subscribers.js
index 2d842bd..1029a3c 100644
--- a/lib/subscribers.js
+++ b/lib/subscribers.js
@@ -84,26 +84,26 @@ module.exports = {
    * @param {callback} callback - Required. A callback
    */
 
-  // TODO: Return an optional Promise
-  updateBatchSubscribers(payload, callback) {
-    const subscribers = payload && payload.batches && payload.batches[0].subscribers || [];
+  updateBatchSubscribers: async function (payload, callback) {
+    const subscribers = (payload && payload.batches && payload.batches[0].subscribers) || [];
     const batchSize = 1000;
     const batches = [];
     const errors = [];
     const responses = [];
     const bodies = [];
     const headers = this.requestHeaders();
-    let done = 0;
     let hasError = false;
 
     // Break the payload into batch-sized chunks
-    for (let i = 0, j = subscribers.length; i < j; i += batchSize) {
-      batches.push(subscribers.slice(i, batchSize));
+    for (let i = 0; i < subscribers.length; i += batchSize) {
+      batches.push(subscribers.slice(i, i + batchSize));
     }
 
-    batches.forEach((batch, batchIndex) => {
-      request.post(
-        {
+    // Map each batch to an axios request and store the results
+    await Promise.all(
+      batches.map((batch, batchIndex) =>
+        request({
+          method: 'post',
           url: `${helpers.baseUrl}v2/${this.accountId}/subscribers/batches`,
           headers,
           responseType: 'json',
@@ -112,24 +112,21 @@ module.exports = {
               subscribers: batch
             }]
           }
-        },
-        (error, response, body) => {
-          errors[batchIndex] = error;
+        })
+        .then((response) => {
           responses[batchIndex] = response;
-          bodies[batchIndex] = body;
-          hasError = hasError || error;
-          done += 1;
+          bodies[batchIndex] = response.data;
+          errors[batchIndex] = null;
+        })
+        .catch((error) => {
+          errors[batchIndex] = error;
+          responses[batchIndex] = null;
+          bodies[batchIndex] = null;
+          hasError = true;
+        })
+      )
+    );
 
-          if (done === batches.length) {
-            // All batches complete; call back
-            callback(
-              hasError ? errors : null,
-              responses,
-              bodies
-            );
-          }
-        }
-      );
-    });
+    callback(hasError ? errors : null, responses, bodies);
   }
 };
diff --git a/spec/lib/subscribers_spec.js b/spec/lib/subscribers_spec.js
index 55a9938..f6dc3a9 100644
--- a/spec/lib/subscribers_spec.js
+++ b/spec/lib/subscribers_spec.js
@@ -1,4 +1,4 @@
-const request = require('axios');
+const axios = require('axios');
 const sinon = require('sinon');
 const client = require('../../lib/index')({ token: 'abc123', accountId: 9999999 });
 
@@ -96,12 +96,11 @@ describe('Subscribers with callback', () => {
     };
 
     beforeEach(() => {
-      sinon.stub(request, 'post')
-        .yields(null, { statusCode: 201 }, {});
+      sinon.stub(axios, 'request').resolves({ status: 201, data: {} });
     });
 
     afterEach(() => {
-      request.post.restore();
+      axios.request.restore();
     });
 
     it('should post batches of subscribers and call request with post', (done) => {
@@ -113,7 +112,7 @@ describe('Subscribers with callback', () => {
         expect(responses[0].statusCode).toBe(201);
         expect(responses[1].statusCode).toBe(201);
         expect(bodies).toEqual([{}, {}]);
-        expect(request.post.callCount).toBe(2);
+        expect(axios.request.callCount).toBe(2);
       });
       done();
     });
@@ -127,13 +126,11 @@ describe('Subscribers with callback', () => {
     };
 
     beforeEach(() => {
-      sinon.stub(request, 'post')
-        .yields(null, { statusCode: 201 }, {});
-      spyOn(request, 'post').and.callThrough();
+      sinon.stub(axios, 'request').resolves({ status: 201, data: {} });
     });
 
     afterEach(() => {
-      request.post.restore();
+      axios.request.restore();
     });
 
     it('should set the correct request URL', (done) => {
@@ -143,9 +140,9 @@ describe('Subscribers with callback', () => {
         expect(responses[0].statusCode).toBe(201);
         expect(bodies).toEqual([{}]);
       });
-      done();
-
-      expect(request.post).toHaveBeenCalledWith({
+    
+      expect(axios.request.calledWith({
+        method: 'post',
         url: 'https://api.getdrip.com/v2/9999999/subscribers/batches',
         headers: client.requestHeaders(),
         responseType: 'json',
@@ -154,7 +151,10 @@ describe('Subscribers with callback', () => {
             subscribers: [undefined]
           }]
         }
-      }, jasmine.any(Function));
+      }));
+
+      done();
+      
     });
   });