diff --git a/src/Graph.ts b/src/Graph.ts
index 0a974892693..eeddda18f30 100644
--- a/src/Graph.ts
+++ b/src/Graph.ts
@@ -166,7 +166,7 @@ export default class Graph {
 			this.getModuleContext = () => this.context;
 		}
 
-		this.acornOptions = options.acorn || {};
+		this.acornOptions = options.acorn ? Object.assign({}, options.acorn) : {};
 		const acornPluginsToInject = [];
 
 		acornPluginsToInject.push(injectImportMeta);
diff --git a/test/misc/misc.js b/test/misc/misc.js
index 4640a9fcbd7..2cd6bf0878a 100644
--- a/test/misc/misc.js
+++ b/test/misc/misc.js
@@ -3,6 +3,27 @@ const rollup = require('../../dist/rollup');
 const { loader } = require('../utils.js');
 
 describe('misc', () => {
+	it('throw modification of options or its property', () => {
+		const { freeze } = Object;
+		return rollup.rollup(
+			freeze({
+				input: 'input',
+				external: freeze([]),
+				plugins: freeze([
+					{
+						name: 'loader',
+						resolveId: freeze(() => 'input'),
+						load: freeze(() => `export default 0;`)
+					}
+				]),
+				acornInjectPlugins: freeze([]),
+				acorn: freeze({}),
+				experimentalTopLevelAwait: true,
+				treeshake: freeze({})
+			})
+		);
+	});
+
 	it('warns if node builtins are unresolved in a non-CJS, non-ES bundle (#1051)', () => {
 		const warnings = [];
 
diff --git a/test/utils.js b/test/utils.js
index d21f62e33d9..2506c74d9d7 100644
--- a/test/utils.js
+++ b/test/utils.js
@@ -117,6 +117,7 @@ function removeOldTest(dir) {
 }
 
 function loader(modules) {
+	modules = Object.assign(Object.create(null), modules);
 	return {
 		resolveId(id) {
 			return id in modules ? id : null;