diff --git a/README.md b/README.md
index da0ed014..714976b7 100644
--- a/README.md
+++ b/README.md
@@ -41,7 +41,7 @@ const webpackConfig = {
     new ElasticAPMSourceMapPlugin({
       serviceName: 'SERVICE_NAME',
       serviceVersion: 'SERVICE_VERSION',
-      serverURL: 'https://ELASTIC_APM_SERVER_URL',
+      serverURL: 'http://127.0.0.1:8200/assets/v1/sourcemaps',
       publicPath: PUBLIC_PATH,
       secret: 'SECRET',
       logLevel: 'debug'
diff --git a/package.json b/package.json
index 241c0bb9..155b69f3 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "elastic-apm-sourcemap-webpack-plugin",
-  "version": "1.3.1",
+  "version": "1.3.2",
   "description": "ElasticAPMSourceMapPlugin is a Webpack plugin that uploads sourcemaps generated by Webpack to a Elastic APM server.",
   "keywords": [
     "elastic",
diff --git a/src/elastic-apm-sourcemap-webpack-plugin.ts b/src/elastic-apm-sourcemap-webpack-plugin.ts
index 92f1d9d6..94675143 100644
--- a/src/elastic-apm-sourcemap-webpack-plugin.ts
+++ b/src/elastic-apm-sourcemap-webpack-plugin.ts
@@ -42,7 +42,10 @@ export default class ElasticAPMSourceMapPlugin implements webpack.Plugin {
           const formData = new FormData();
           const bundleFilePath = `${this.config.publicPath}/${sourceFile}`;
 
-          formData.append('sourcemap', compilation.assets[sourceMap].source());
+          formData.append('sourcemap', compilation.assets[sourceMap].source(), {
+            filename: sourceMap,
+            contentType: 'application/json'
+          });
           formData.append('service_version', this.config.serviceVersion);
           formData.append('bundle_filepath', bundleFilePath);
           formData.append('service_name', this.config.serviceName);
@@ -51,6 +54,10 @@ export default class ElasticAPMSourceMapPlugin implements webpack.Plugin {
             ? { Authorization: `Bearer ${this.config.secret}` }
             : undefined;
 
+          logger.debug(
+            `uploading ${sourceMap} to Elastic APM with bundle_filepath: ${bundleFilePath}.`
+          );
+
           return fetch(this.config.serverURL, {
             method: 'POST',
             body: formData,
@@ -59,10 +66,7 @@ export default class ElasticAPMSourceMapPlugin implements webpack.Plugin {
             .then(response => Promise.all([response.ok, response.text()]))
             .then(([ok, responseText]) => {
               if (ok) {
-                logger.debug(`APM server response: ${responseText}`);
-                logger.debug(
-                  `uploaded ${sourceMap} to Elastic APM with bundle_filepath: ${bundleFilePath}.`
-                );
+                logger.debug(`uploaded ${sourceMap}.`);
               } else {
                 logger.error(`APM server response: ${responseText}`);
                 throw new Error(`error while uploading ${sourceMap} to Elastic APM`);