diff --git a/android/src/main/java/com/reactlibrary/RNImgToBase64Module.java b/android/src/main/java/com/reactlibrary/RNImgToBase64Module.java
index 7a7b8b7..c049162 100644
--- a/android/src/main/java/com/reactlibrary/RNImgToBase64Module.java
+++ b/android/src/main/java/com/reactlibrary/RNImgToBase64Module.java
@@ -12,7 +12,7 @@
 import com.facebook.react.bridge.ReactApplicationContext;
 import com.facebook.react.bridge.ReactContextBaseJavaModule;
 import com.facebook.react.bridge.ReactMethod;
-import com.facebook.react.bridge.Callback;
+import com.facebook.react.bridge.Promise;
 
 public class RNImgToBase64Module extends ReactContextBaseJavaModule {
 
@@ -29,13 +29,13 @@ public String getName() {
   }
 
   @ReactMethod
-  public void getBase64String(String uri, Callback callback) {
+  public void getBase64String(String uri, Promise promise) {
     try {
       Bitmap image = MediaStore.Images.Media.getBitmap(reactContext.getContentResolver(), Uri.parse(uri));
       if (image == null) {
-        callback.invoke("Failed to decode Bitmap, uri: " + uri);
+        promise.reject("Error", "Failed to decode Bitmap, uri: " + uri);
       } else {
-        callback.invoke(null, bitmapToBase64(image));
+        promise.resolve(bitmapToBase64(image));
       }
     } catch (Error e) {
       e.printStackTrace();
diff --git a/ios/RNImgToBase64.m b/ios/RNImgToBase64.m
index 360c1e6..b286173 100644
--- a/ios/RNImgToBase64.m
+++ b/ios/RNImgToBase64.m
@@ -10,11 +10,14 @@ - (dispatch_queue_t)methodQueue
 RCT_EXPORT_MODULE()
 
 #pragma mark getBase64String
-RCT_EXPORT_METHOD(getBase64String:(NSURL*)url callback:(RCTResponseSenderBlock)callback) {
+RCT_EXPORT_METHOD(getBase64String:(NSURL*)url
+    resolve:(RCTPromiseResolveBlock)resolve
+    rejecter:(RCTPromiseRejectBlock)reject
+) {
     dispatch_async(dispatch_queue_create("image_processing", 0), ^{
         NSData* data = [NSData dataWithContentsOfURL:url];
         dispatch_async(dispatch_get_main_queue(), ^{
-            callback(@[[NSNull null], [data base64EncodedStringWithOptions:0]]);
+            resolve([data base64EncodedStringWithOptions:0]);
         });
     });
 }
diff --git a/package.json b/package.json
index b73ef48..3c6de75 100644
--- a/package.json
+++ b/package.json
@@ -1,7 +1,7 @@
 
 {
   "name": "react-native-image-base64",
-  "version": "0.1.1",
+  "version": "0.1.2",
   "description": "Convert image to base64",
   "main": "index.js",
   "scripts": {