diff --git a/lib/builder/builder.js b/lib/builder/builder.js
index 92293c05f8..62970aa943 100644
--- a/lib/builder/builder.js
+++ b/lib/builder/builder.js
@@ -446,8 +446,9 @@ export default class Builder {
 
     // Check plugins exist then set alias to their real path
     await Promise.all(this.plugins.map(async (p) => {
-      if (!await fsExtra.pathExists(p.src)) {
-        throw new Error(`Plugin not found: ${p.src}`)
+      const pluginFile = `${p.src}${path.extname(p.src) ? '' : '.js'}`
+      if (!await fsExtra.pathExists(pluginFile)) {
+        throw new Error(`Plugin not found: ${pluginFile}`)
       }
 
       const src = this.relativeToBuild(p.src)
diff --git a/test/fixtures/with-config/nuxt.config.js b/test/fixtures/with-config/nuxt.config.js
index 5fb322ca3f..1805f4410a 100644
--- a/test/fixtures/with-config/nuxt.config.js
+++ b/test/fixtures/with-config/nuxt.config.js
@@ -26,7 +26,7 @@ export default {
   loadingIndicator: 'circle',
   extensions: 'ts',
   plugins: [
-    '~/plugins/test.js',
+    '~/plugins/test',
     { src: '~/plugins/only-client.js', ssr: false }
   ],
   loading: '~/components/loading',