diff --git a/dev/server.js b/dev/server.js
index 1477e3ec..7ec1e065 100644
--- a/dev/server.js
+++ b/dev/server.js
@@ -90,7 +90,7 @@ class ServerExample {
 
         responseJson.success = 1;
         responseJson.file = {
-          url: image.filepath,
+          url: 'file://' + image.filepath,
           name: image.newFilename,
           size: image.size
         };
diff --git a/src/types/types.ts b/src/types/types.ts
index f4b564f6..53945d7c 100644
--- a/src/types/types.ts
+++ b/src/types/types.ts
@@ -117,12 +117,12 @@ export interface ImageConfig {
   /**
    * Field name for the uploaded image.
    */
-  field?: string;
+  field: string;
 
   /**
    * Allowed mime-types for the uploaded image.
    */
-  types?: string;
+  types: string;
 
   /**
    * Placeholder text for the caption field.
diff --git a/src/uploader.ts b/src/uploader.ts
index 3f456ba9..006b4690 100644
--- a/src/uploader.ts
+++ b/src/uploader.ts
@@ -72,7 +72,7 @@ export default class Uploader {
     // custom uploading
     if (this.config.uploader && typeof this.config.uploader.uploadByFile === 'function') {
       const uploadByFile = this.config.uploader.uploadByFile;
-      upload = ajax.selectFiles({ accept: this.config.types || 'image/*'}).then((files: File[]) => {
+      upload = ajax.selectFiles({ accept: this.config.types}).then((files: File[]) => {
         preparePreview(files[0]);
 
         const customUpload = uploadByFile(files[0]);
@@ -181,7 +181,7 @@ export default class Uploader {
        */
       const formData = new FormData();
 
-      formData.append(this.config.field || 'image', file);
+      formData.append(this.config.field, file);
 
       if (this.config.additionalRequestData && Object.keys(this.config.additionalRequestData).length) {
         Object.entries(this.config.additionalRequestData).forEach(([name, value]: [string, any]) => {