diff --git a/docs/config/README.md b/docs/config/README.md
index 5f574ffe66..359d09d264 100644
--- a/docs/config/README.md
+++ b/docs/config/README.md
@@ -363,10 +363,10 @@ See [the plugin's README](https://github.com/vuejs/vue-cli/blob/dev/packages/%40
 
 ### parallel
 
-- Type: `boolean`
+- Type: `boolean | number`
 - Default: `require('os').cpus().length > 1`
 
-  Whether to use `thread-loader` for Babel or TypeScript transpilation. This is enabled for production builds when the system has more than 1 CPU cores.
+  Whether to use `thread-loader` for Babel or TypeScript transpilation. This is enabled for production builds when the system has more than 1 CPU cores. Passing a number will define the amount of workers used.
 
 ### pwa