diff --git a/src/backups.js b/src/backups.js
index d4ddfee0d..60a3a2dc4 100644
--- a/src/backups.js
+++ b/src/backups.js
@@ -84,7 +84,7 @@ function api(provider) {
     switch (provider) {
         case 'caas': return caas;
         case 's3': return s3;
-        case 'fs': return filesystem;
+        case 'filesystem': return filesystem;
         default: return null;
     }
 }
diff --git a/src/storage/filesystem.js b/src/storage/filesystem.js
index 87df94953..35df79c38 100644
--- a/src/storage/filesystem.js
+++ b/src/storage/filesystem.js
@@ -35,7 +35,7 @@ function getAppBackupDetails(apiConfig, appId, dataId, configId, callback) {
     assert.strictEqual(typeof apiConfig, 'object');
     assert.strictEqual(typeof appId, 'string');
     assert.strictEqual(typeof dataId, 'string');
-    assert.strictEqual(typeof configId, '');
+    assert.strictEqual(typeof configId, 'string');
     assert.strictEqual(typeof callback, 'function');
 
     var backupFolder = apiConfig.backupFolder || FALLBACK_BACKUP_FOLDER;
diff --git a/src/storage/interface.js b/src/storage/interface.js
index c0107aedc..b463ceebd 100644
--- a/src/storage/interface.js
+++ b/src/storage/interface.js
@@ -34,7 +34,7 @@ function getAppBackupDetails(apiConfig, appId, dataId, configId, callback) {
     assert.strictEqual(typeof apiConfig, 'object');
     assert.strictEqual(typeof appId, 'string');
     assert.strictEqual(typeof dataId, 'string');
-    assert.strictEqual(typeof configId, '');
+    assert.strictEqual(typeof configId, 'string');
     assert.strictEqual(typeof callback, 'function');
 
     // Result: { backupScriptArguments: [] }
diff --git a/src/storage/s3.js b/src/storage/s3.js
index 69e1a16e3..98dc247b3 100644
--- a/src/storage/s3.js
+++ b/src/storage/s3.js
@@ -51,7 +51,7 @@ function getAppBackupDetails(apiConfig, appId, dataId, configId, callback) {
     assert.strictEqual(typeof apiConfig, 'object');
     assert.strictEqual(typeof appId, 'string');
     assert.strictEqual(typeof dataId, 'string');
-    assert.strictEqual(typeof configId, '');
+    assert.strictEqual(typeof configId, 'string');
     assert.strictEqual(typeof callback, 'function');
 
     var s3DataUrl = 's3://' + apiConfig.bucket + '/' + apiConfig.prefix + '/' + dataId;