diff --git a/.gitignore b/.gitignore
index 26c4811..5e975b2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -21,3 +21,4 @@ DerivedData
 .idea/
 # Pods - for those of you who use CocoaPods
 Pods
+update-test.sh
diff --git a/FS.common.js b/FS.common.js
index 60f4fe0..ca773df 100644
--- a/FS.common.js
+++ b/FS.common.js
@@ -134,9 +134,7 @@ var RNFS = {
       .catch(convertError);
   },
 
-  MainBundle: RNFSManager.MainBundleDirectory,
-  CachesDirectory: RNFSManager.NSCachesDirectory,
-  DocumentDirectory: RNFSManager.NSDocumentDirectory,
+  MainBundlePath: RNFSManager.MainBundlePath,
   CachesDirectoryPath: RNFSManager.NSCachesDirectoryPath,
   DocumentDirectoryPath: RNFSManager.NSDocumentDirectoryPath
 };
diff --git a/README.md b/README.md
index 761987e..85a321b 100644
--- a/README.md
+++ b/README.md
@@ -89,7 +89,7 @@ public class MainActivity extends Activity implements DefaultHardwareBackBtnHand
 var RNFS = require('react-native-fs');
 
 // get a list of files and directories in the main bundle
-RNFS.readDir('/', RNFS.MainBundle)
+RNFS.readDir(RNFS.MainBundlePath)
   .then((result) => {
     console.log('GOT RESULT', result);
 
@@ -157,11 +157,8 @@ return RNFS.unlink(path)
 
 The following constants are available on the `RNFS` export:
 
-`MainBundle` (`Number`) The identifier for the main bundle  
-`CachesDirectory` (`Number`) The identifier for the caches  directory  
-`DocumentDirectory` (`Number`) The identifier for the document directory
-
-`CachesDirectoryPath` (`String`) The absolute path to the caches directory
+`MainBundlePath` (`String`) The absolute path to the main bundle directory  
+`CachesDirectoryPath` (`String`) The absolute path to the caches directory  
 `DocumentDirectoryPath`  (`String`) The absolute path to the document directory
 
 ### `promise readDir(path)`
@@ -171,7 +168,7 @@ Reads the contents of `path`. This must be an absolute path. Use the above path
 The returned promise resolves with an array of objects with the following properties:
 
 `name` (`String`), The name of the item  
-`path` (`String`), The absolute path to the item
+`path` (`String`), The absolute path to the item  
 `size` (`Number`), Size in bytes
 
 ### `promise readdir(path)`
diff --git a/RNFSManager.m b/RNFSManager.m
index e892763..3846702 100644
--- a/RNFSManager.m
+++ b/RNFSManager.m
@@ -12,8 +12,6 @@
 
 @implementation RNFSManager
 
-static int MainBundleDirectory = 999;
-
 RCT_EXPORT_MODULE();
 
 - (dispatch_queue_t)methodQueue
@@ -144,13 +142,19 @@ RCT_EXPORT_METHOD(downloadFile:(NSString *)urlStr
                   filepath:(NSString *)filepath
                   callback:(RCTResponseSenderBlock)callback)
 {
+  NSError *error = nil;
+
   NSURL *url = [NSURL URLWithString:urlStr];
-  NSData *urlData = [NSData dataWithContentsOfURL:url];
+  NSData *urlData = [NSData dataWithContentsOfURL:url options:NSDataReadingUncached error:&error];
 
-  BOOL success = NO;
+  if (error) {
+    return callback([self makeErrorPayload:error]);
+  }
 
-  if (urlData) {
-    success = [urlData writeToFile:filepath atomically:YES];
+  BOOL success = [urlData writeToFile:filepath atomically:YES];
+
+  if (!success) {
+    return callback(@[[NSString stringWithFormat:@"Could not write downloaded data to file at path %@", filepath]]);
   }
 
   callback(@[[NSNull null], [NSNumber numberWithBool:success], filepath]);
@@ -203,11 +207,9 @@ RCT_EXPORT_METHOD(pathForBundle:(NSString *)bundleNamed
 - (NSDictionary *)constantsToExport
 {
   return @{
+    @"MainBundlePath": [[NSBundle mainBundle] bundlePath],
     @"NSCachesDirectoryPath": [self getPathForDirectory:NSCachesDirectory],
     @"NSDocumentDirectoryPath": [self getPathForDirectory:NSDocumentDirectory],
-    @"NSCachesDirectory": [NSNumber numberWithInteger:NSCachesDirectory],
-    @"NSDocumentDirectory": [NSNumber numberWithInteger:NSDocumentDirectory],
-    @"MainBundleDirectory": [NSNumber numberWithInteger:MainBundleDirectory],
     @"NSFileTypeRegular": NSFileTypeRegular,
     @"NSFileTypeDirectory": NSFileTypeDirectory
   };