diff --git a/src/backups.js b/src/backups.js
index dffa9a1a2..7c4438c7f 100644
--- a/src/backups.js
+++ b/src/backups.js
@@ -226,7 +226,7 @@ function backupBoxWithAppBackupIds(appBackupIds, prefix, callback) {
             `/usr/bin/mysqldump -u root ${password} --single-transaction --routines \
                 --triggers ${config.database().name} > "${paths.BOX_DATA_DIR}/box.mysqldump"`
         ];
-        shell.exec('backupBox', '/bin/bash', mysqlDumpArgs, function (error) {
+        shell.exec('backupBox', '/bin/bash', mysqlDumpArgs, { }, function (error) {
             if (error) return callback(new BackupsError(BackupsError.INTERNAL_ERROR, error));
 
             backupdb.add({ id: backupId, version: config.version(), type: backupdb.BACKUP_TYPE_BOX, dependsOn: appBackupIds, restoreConfig: null }, function (error) {
diff --git a/src/shell.js b/src/shell.js
index 88594adf5..3c9a1cfcc 100644
--- a/src/shell.js
+++ b/src/shell.js
@@ -33,13 +33,8 @@ function exec(tag, file, args, options, callback) {
     assert.strictEqual(typeof tag, 'string');
     assert.strictEqual(typeof file, 'string');
     assert(util.isArray(args));
-
-    if (typeof options === 'function') {
-        callback = options;
-        options = { };
-    }
-
     assert.strictEqual(typeof options, 'object');
+    assert.strictEqual(typeof callback, 'function');
 
     callback = once(callback); // exit may or may not be called after an 'error'
 
diff --git a/src/test/shell-test.js b/src/test/shell-test.js
index ac17f7f06..9ffbee28c 100644
--- a/src/test/shell-test.js
+++ b/src/test/shell-test.js
@@ -12,7 +12,7 @@ var expect = require('expect.js'),
 
 describe('shell', function () {
     it('can run valid program', function (done) {
-        var cp = shell.exec('test', 'ls', [ '-l' ], function (error) {
+        var cp = shell.exec('test', 'ls', [ '-l' ], { }, function (error) {
             expect(cp).to.be.ok();
             expect(error).to.be(null);
             done();
@@ -20,14 +20,14 @@ describe('shell', function () {
     });
 
     it('fails on invalid program', function (done) {
-        var cp = shell.exec('test', 'randomprogram', [ ], function (error) {
+        var cp = shell.exec('test', 'randomprogram', [ ], { }, function (error) {
             expect(error).to.be.ok();
             done();
         });
     });
 
     it('fails on failing program', function (done) {
-        var cp = shell.exec('test', '/usr/bin/false', [ ], function (error) {
+        var cp = shell.exec('test', '/usr/bin/false', [ ], { }, function (error) {
             expect(error).to.be.ok();
             done();
         });
@@ -63,4 +63,3 @@ describe('shell', function () {
         done();
     });
 });
-