diff --git a/packages/runtime-core/src/apiDefineComponent.ts b/packages/runtime-core/src/apiDefineComponent.ts
index 9edb9965e..76e9567fe 100644
--- a/packages/runtime-core/src/apiDefineComponent.ts
+++ b/packages/runtime-core/src/apiDefineComponent.ts
@@ -279,6 +279,9 @@ export function defineComponent(
   extraOptions?: ComponentOptions
 ) {
   return isFunction(options)
-    ? extend({ name: options.name }, extraOptions, { setup: options })
+    ? // #8326: extend call and options.name access are considered side-effects
+      // by Rollup, so we have to wrap it in a pure-annotated IIFE.
+      /*#__PURE__*/ (() =>
+        extend({ name: options.name }, extraOptions, { setup: options }))()
     : options
 }