diff --git a/packages/playground/ssr-webworker/vite.config.js b/packages/playground/ssr-webworker/vite.config.js
index 80cc1784cdc565..91a0571380608e 100644
--- a/packages/playground/ssr-webworker/vite.config.js
+++ b/packages/playground/ssr-webworker/vite.config.js
@@ -10,9 +10,18 @@ module.exports = {
   },
   ssr: {
     target: 'webworker',
-    noExternal: true
+    noExternal: ['this-should-be-replaced-by-the-boolean']
   },
   plugins: [
+    {
+      config() {
+        return {
+          ssr: {
+            noExternal: true
+          }
+        }
+      }
+    },
     {
       config() {
         return {
diff --git a/packages/vite/src/node/config.ts b/packages/vite/src/node/config.ts
index 556fcf7cbae77a..d242ac632c220e 100644
--- a/packages/vite/src/node/config.ts
+++ b/packages/vite/src/node/config.ts
@@ -745,7 +745,8 @@ function mergeConfigRecursively(
     } else if (key === 'assetsInclude' && rootPath === '') {
       merged[key] = [].concat(existing, value)
       continue
-    } else if (key === 'noExternal' && existing === true) {
+    } else if (key === 'noExternal' && (existing === true || value === true)) {
+      merged[key] = true
       continue
     }