diff --git a/src/backupformat/tgz.js b/src/backupformat/tgz.js
index cef1488c0..d0dd42a7c 100644
--- a/src/backupformat/tgz.js
+++ b/src/backupformat/tgz.js
@@ -29,10 +29,9 @@ function getBackupFilePath(backupConfig, remotePath) {
     return path.join(rootPath, remotePath + fileType);
 }
 
-function tarPack(dataLayout, encryption, callback) {
+function tarPack(dataLayout, encryption) {
     assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
     assert.strictEqual(typeof encryption, 'object');
-    assert.strictEqual(typeof callback, 'function');
 
     const pack = tar.pack('/', {
         dereference: false, // pack the symlink and not what it points to
@@ -76,14 +75,13 @@ function tarPack(dataLayout, encryption, callback) {
         pack.pipe(gzip).pipe(ps);
     }
 
-    return callback(null, ps);
+    return ps;
 }
 
-function tarExtract(inStream, dataLayout, encryption, callback) {
+function tarExtract(inStream, dataLayout, encryption) {
     assert.strictEqual(typeof inStream, 'object');
     assert(dataLayout instanceof DataLayout, 'dataLayout must be a DataLayout');
     assert.strictEqual(typeof encryption, 'object');
-    assert.strictEqual(typeof callback, 'function');
 
     const gunzip = zlib.createGunzip({});
     const ps = progressStream({ time: 10000 }); // display a progress every 10 seconds
@@ -122,7 +120,7 @@ function tarExtract(inStream, dataLayout, encryption, callback) {
     });
 
     if (encryption) {
-        let decrypt = new DecryptStream(encryption);
+        const decrypt = new DecryptStream(encryption);
         decrypt.on('error', function (error) {
             debug('tarExtract: decrypt stream error.', error);
             emitError(new BoxError(BoxError.EXTERNAL_ERROR, `Failed to decrypt: ${error.message}`));
@@ -132,7 +130,7 @@ function tarExtract(inStream, dataLayout, encryption, callback) {
         inStream.pipe(ps).pipe(gunzip).pipe(extract);
     }
 
-    callback(null, ps);
+    return ps;
 }
 
 function download(backupConfig, remotePath, dataLayout, progressCallback, callback) {
@@ -152,17 +150,15 @@ function download(backupConfig, remotePath, dataLayout, progressCallback, callba
         storage.api(backupConfig.provider).download(backupConfig, backupFilePath, function (error, sourceStream) {
             if (error) return retryCallback(error);
 
-            tarExtract(sourceStream, dataLayout, backupConfig.encryption, function (error, ps) {
-                if (error) return retryCallback(error);
+            const ps = tarExtract(sourceStream, dataLayout, backupConfig.encryption);
 
-                ps.on('progress', function (progress) {
-                    const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
-                    if (!transferred && !speed) return progressCallback({ message: 'Downloading backup' }); // 0M@0MBps looks wrong
-                    progressCallback({ message: `Downloading ${transferred}M@${speed}MBps` });
-                });
-                ps.on('error', retryCallback);
-                ps.on('done', retryCallback);
+            ps.on('progress', function (progress) {
+                const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
+                if (!transferred && !speed) return progressCallback({ message: 'Downloading backup' }); // 0M@0MBps looks wrong
+                progressCallback({ message: `Downloading ${transferred}M@${speed}MBps` });
             });
+            ps.on('error', retryCallback);
+            ps.on('done', retryCallback);
         });
     }, callback);
 }
@@ -177,17 +173,15 @@ function upload(backupConfig, remotePath, dataLayout, progressCallback, callback
     async.retry({ times: 5, interval: 20000 }, function (retryCallback) {
         retryCallback = once(retryCallback); // protect again upload() erroring much later after tar stream error
 
-        tarPack(dataLayout, backupConfig.encryption, function (error, tarStream) {
-            if (error) return retryCallback(error);
+        const tarStream = tarPack(dataLayout, backupConfig.encryption);
 
-            tarStream.on('progress', function (progress) {
-                const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
-                if (!transferred && !speed) return progressCallback({ message: 'Uploading backup' }); // 0M@0MBps looks wrong
-                progressCallback({ message: `Uploading backup ${transferred}M@${speed}MBps` });
-            });
-            tarStream.on('error', retryCallback); // already returns BoxError
-
-            storage.api(backupConfig.provider).upload(backupConfig, getBackupFilePath(backupConfig, remotePath), tarStream, retryCallback);
+        tarStream.on('progress', function (progress) {
+            const transferred = Math.round(progress.transferred/1024/1024), speed = Math.round(progress.speed/1024/1024);
+            if (!transferred && !speed) return progressCallback({ message: 'Uploading backup' }); // 0M@0MBps looks wrong
+            progressCallback({ message: `Uploading backup ${transferred}M@${speed}MBps` });
         });
+        tarStream.on('error', retryCallback); // already returns BoxError
+
+        storage.api(backupConfig.provider).upload(backupConfig, getBackupFilePath(backupConfig, remotePath), tarStream, retryCallback);
     }, callback);
 }