diff --git a/packages/lib/file-api-driver-amazon-s3.js b/packages/lib/file-api-driver-amazon-s3.js
index 6e202db26..ddb187b4b 100644
--- a/packages/lib/file-api-driver-amazon-s3.js
+++ b/packages/lib/file-api-driver-amazon-s3.js
@@ -2,6 +2,7 @@ const { basicDelta } = require('./file-api');
 const { basename } = require('./path-utils');
 const shim = require('./shim').default;
 const JoplinError = require('./JoplinError');
+const { Buffer } = require('buffer');
 
 const S3_MAX_DELETES = 1000;
 
@@ -83,12 +84,14 @@ class FileApiDriverAmazonS3 {
 
 	async s3UploadFileFrom(path, key) {
 		if (!shim.fsDriver().exists(path)) throw new Error('s3UploadFileFrom: file does not exist');
-		const body = await shim.fsDriver().readFile(path, 'Buffer');
+		const body = await shim.fsDriver().readFile(path, 'base64');
+		const fileStat = await shim.fsDriver().stat(path);
 		return new Promise((resolve, reject) => {
-			this.api().upload({
+			this.api().putObject({
 				Bucket: this.s3_bucket_,
 				Key: key,
-				Body: body,
+				Body: Buffer.from(body, 'base64'),
+				ContentLength: `${fileStat.size}`,
 			}, (err, response) => {
 				if (err) reject(err);
 				else resolve(response);