diff --git a/x-pack/legacy/plugins/apm/scripts/optimize-tsconfig/optimize.js b/x-pack/legacy/plugins/apm/scripts/optimize-tsconfig/optimize.js
index 83147bce0d6bc..3a5809e564691 100644
--- a/x-pack/legacy/plugins/apm/scripts/optimize-tsconfig/optimize.js
+++ b/x-pack/legacy/plugins/apm/scripts/optimize-tsconfig/optimize.js
@@ -11,7 +11,6 @@ const { promisify } = require('util');
 const path = require('path');
 const json5 = require('json5');
 const execa = require('execa');
-const { assign } = require('lodash');
 
 const readFile = promisify(fs.readFile);
 const writeFile = promisify(fs.writeFile);
@@ -55,7 +54,7 @@ async function addApmFilesToXpackTsConfig() {
 
   await writeFile(
     xpackTsConfig,
-    JSON.stringify(assign(config, template), null, 2),
+    JSON.stringify({ ...config, ...template }, null, 2),
     { encoding: 'utf-8' }
   );
 }