diff --git a/packages/playground/ssr-webworker/vite.config.js b/packages/playground/ssr-webworker/vite.config.js
index d0e80179498685..82fdf7579e9752 100644
--- a/packages/playground/ssr-webworker/vite.config.js
+++ b/packages/playground/ssr-webworker/vite.config.js
@@ -8,5 +8,16 @@ module.exports = {
   ssr: {
     target: 'webworker',
     noExternal: true
-  }
+  },
+  plugins: [
+    {
+      config() {
+        return {
+          ssr: {
+            noExternal: ['this-should-not-replace-the-boolean']
+          }
+        }
+      }
+    }
+  ]
 }
diff --git a/packages/vite/src/node/config.ts b/packages/vite/src/node/config.ts
index 539b26205d0bc6..19274a725d785a 100644
--- a/packages/vite/src/node/config.ts
+++ b/packages/vite/src/node/config.ts
@@ -657,6 +657,8 @@ function mergeConfigRecursively(
       } else if (key === 'assetsInclude' && rootPath === '') {
         merged[key] = [].concat(existing, value)
         continue
+      } else if (key === 'noExternal' && existing === true) {
+        continue
       }
     }