diff --git a/LICENSE.md b/LICENSE.md
index b362d602a05..cdbe1bcf8b9 100644
--- a/LICENSE.md
+++ b/LICENSE.md
@@ -28,12 +28,12 @@ The published Rollup artifact additionally contains code with the following lice
 MIT, ISC
 
 # Bundled dependencies:
-## acorn-class-fields
+## acorn
 License: MIT
-By: Adrian Heine
-Repository: https://github.com/acornjs/acorn-class-fields
+By: Marijn Haverbeke, Ingvar Stepanyan, Adrian Heine
+Repository: https://github.com/acornjs/acorn.git
 
-> Copyright (C) 2017-2018 by Adrian Heine
+> Copyright (C) 2012-2018 by various contributors (see AUTHORS)
 > 
 > Permission is hereby granted, free of charge, to any person obtaining a copy
 > of this software and associated documentation files (the "Software"), to deal
@@ -55,10 +55,10 @@ Repository: https://github.com/acornjs/acorn-class-fields
 
 ---------------------------------------
 
-## acorn-import-meta
+## acorn-class-fields
 License: MIT
 By: Adrian Heine
-Repository: https://github.com/adrianheine/acorn-import-meta
+Repository: https://github.com/acornjs/acorn-class-fields
 
 > Copyright (C) 2017-2018 by Adrian Heine
 > 
@@ -316,33 +316,6 @@ Repository: jonschlinkert/fill-range
 
 ---------------------------------------
 
-## fork-acorn-optional-chaining
-License: MIT
-By: Marijn Haverbeke, Ingvar Stepanyan, Adrian Heine
-Repository: https://github.com/acornjs/acorn.git
-
-> Copyright (C) 2012-2018 by various contributors (see AUTHORS)
-> 
-> Permission is hereby granted, free of charge, to any person obtaining a copy
-> of this software and associated documentation files (the "Software"), to deal
-> in the Software without restriction, including without limitation the rights
-> to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-> copies of the Software, and to permit persons to whom the Software is
-> furnished to do so, subject to the following conditions:
-> 
-> The above copyright notice and this permission notice shall be included in
-> all copies or substantial portions of the Software.
-> 
-> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-> IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-> FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-> AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-> LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-> OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-> THE SOFTWARE.
-
----------------------------------------
-
 ## glob-parent
 License: ISC
 By: Gulp Team, Elan Shanker, Blaine Bublitz
diff --git a/package-lock.json b/package-lock.json
index c20637fb152..1a4f626981d 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -539,18 +539,18 @@
       "dev": true
     },
     "acorn": {
-      "version": "7.2.0",
-      "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.2.0.tgz",
-      "integrity": "sha512-apwXVmYVpQ34m/i71vrApRrRKCWQnZZF1+npOD0WV5xZFfwWOmKGQ2RWlfdy9vWITsenisM8M0Qeq8agcFHNiQ==",
+      "version": "7.3.1",
+      "resolved": "https://registry.npmjs.org/acorn/-/acorn-7.3.1.tgz",
+      "integrity": "sha512-tLc0wSnatxAQHVHUapaHdz72pi9KUyHjq5KyHjGg9Y8Ifdc79pTh2XvI6I1/chZbnM7QtNKzh66ooDogPZSleA==",
       "dev": true
     },
     "acorn-class-fields": {
-      "version": "0.3.4",
-      "resolved": "https://registry.npmjs.org/acorn-class-fields/-/acorn-class-fields-0.3.4.tgz",
-      "integrity": "sha512-yqUCIu0UJHFmCVhH3Cq29UR+3OJo1CtNWf1ncxTf3KfdEDt7aD0iVYmX7UN+RvIHyOsgukzplQhNkgePtASLUw==",
+      "version": "0.3.6",
+      "resolved": "https://registry.npmjs.org/acorn-class-fields/-/acorn-class-fields-0.3.6.tgz",
+      "integrity": "sha512-nOzMl1byCFAJLgxNUG7QorpzRHWlkBKVSSOMKUu+bVbVZG5lU4NZkOp/uA7CnE+NAsWhmxTsMgQdHsQXUO8Ulg==",
       "dev": true,
       "requires": {
-        "acorn-private-class-elements": "^0.2.5"
+        "acorn-private-class-elements": "^0.2.6"
       }
     },
     "acorn-dynamic-import": {
@@ -559,12 +559,6 @@
       "integrity": "sha512-d3OEjQV4ROpoflsnUA8HozoIR504TFxNivYEUi6uwz0IYhBkTDXGuWlNdMtybRt3nqVx/L6XqMt0FxkXuWKZhw==",
       "dev": true
     },
-    "acorn-import-meta": {
-      "version": "1.1.0",
-      "resolved": "https://registry.npmjs.org/acorn-import-meta/-/acorn-import-meta-1.1.0.tgz",
-      "integrity": "sha512-pshgiVR5mhpjFVdizKTN+kAGRqjJFUOEB3TvpQ6kiAutb1lvHrIVVcGoe5xzMpJkVNifCeymMG7/tsDkWn8CdQ==",
-      "dev": true
-    },
     "acorn-jsx": {
       "version": "5.2.0",
       "resolved": "https://registry.npmjs.org/acorn-jsx/-/acorn-jsx-5.2.0.tgz",
@@ -572,18 +566,18 @@
       "dev": true
     },
     "acorn-private-class-elements": {
-      "version": "0.2.5",
-      "resolved": "https://registry.npmjs.org/acorn-private-class-elements/-/acorn-private-class-elements-0.2.5.tgz",
-      "integrity": "sha512-3eApRrJmPjaxWB3XidP8YMeVq9pcswPFE0KsSWVuhceCU68ZS8fkcf0fTXGhCmnNd7n48NWWV27EKMFPeCoJLg==",
+      "version": "0.2.6",
+      "resolved": "https://registry.npmjs.org/acorn-private-class-elements/-/acorn-private-class-elements-0.2.6.tgz",
+      "integrity": "sha512-PV+AhOU1/vCx5zIBgGYLB5+OoT8IPKZUcWEGdLBTQgFBMMzPM9S5SKSG4EdiuULqoq3pV3C07rGuSC1Y5gbi/g==",
       "dev": true
     },
     "acorn-static-class-features": {
-      "version": "0.2.2",
-      "resolved": "https://registry.npmjs.org/acorn-static-class-features/-/acorn-static-class-features-0.2.2.tgz",
-      "integrity": "sha512-B7aWeS7MXqdgP3RnettN/CFz7HevAlQWfh5zkc3LJzeCQoF1InTzYBCfkkbmit1p0pmCEB8IG05gB62pOm5lvA==",
+      "version": "0.2.3",
+      "resolved": "https://registry.npmjs.org/acorn-static-class-features/-/acorn-static-class-features-0.2.3.tgz",
+      "integrity": "sha512-N7yRI9NduTJRam3BQTXHLR63ykHQv2MnxWTRq0+4PfQosGUz/tM0/ToRqWUqGphP960mDTm/7zJFx3dB/AZtiw==",
       "dev": true,
       "requires": {
-        "acorn-private-class-elements": "^0.2.3"
+        "acorn-private-class-elements": "^0.2.6"
       }
     },
     "acorn-walk": {
@@ -1837,12 +1831,6 @@
         "signal-exit": "^3.0.2"
       }
     },
-    "fork-acorn-optional-chaining": {
-      "version": "7.2.0",
-      "resolved": "https://registry.npmjs.org/fork-acorn-optional-chaining/-/fork-acorn-optional-chaining-7.2.0.tgz",
-      "integrity": "sha512-WM85polHQ1XC5XZ/CWBgaFBjKZ2ooTS42Xcp2vpAemHRNubRG6lGZ5ViTcS5pBh9x5VL2yS2gUO3FVwr9vSA+w==",
-      "dev": true
-    },
     "fromentries": {
       "version": "1.2.0",
       "resolved": "https://registry.npmjs.org/fromentries/-/fromentries-1.2.0.tgz",
diff --git a/package.json b/package.json
index bf120b674b6..cb5bcaf7fca 100644
--- a/package.json
+++ b/package.json
@@ -75,11 +75,10 @@
     "@types/require-relative": "^0.8.0",
     "@types/signal-exit": "^3.0.0",
     "@types/yargs-parser": "^15.0.0",
-    "acorn": "^7.2.0",
-    "acorn-class-fields": "^0.3.4",
-    "acorn-import-meta": "^1.1.0",
+    "acorn": "^7.3.1",
+    "acorn-class-fields": "^0.3.6",
     "acorn-jsx": "^5.2.0",
-    "acorn-static-class-features": "^0.2.2",
+    "acorn-static-class-features": "^0.2.3",
     "acorn-walk": "^7.1.1",
     "buble": "^0.20.0",
     "chokidar": "^3.4.0",
@@ -94,7 +93,6 @@
     "eslint-plugin-import": "^2.21.1",
     "execa": "^4.0.2",
     "fixturify": "^2.1.0",
-    "fork-acorn-optional-chaining": "^7.2.0",
     "hash.js": "^1.1.7",
     "husky": "^4.2.5",
     "is-reference": "^1.2.0",
diff --git a/rollup.config.js b/rollup.config.js
index 8374803a285..28445f9c021 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -49,8 +49,7 @@ const moduleAliases = {
 	resolve: ['.js', '.json', '.md'],
 	entries: [
 		{ find: 'help.md', replacement: path.resolve('cli/help.md') },
-		{ find: 'package.json', replacement: path.resolve('package.json') },
-		{find: 'acorn', replacement: 'fork-acorn-optional-chaining'}
+		{ find: 'package.json', replacement: path.resolve('package.json') }
 	]
 };
 
diff --git a/src/Graph.ts b/src/Graph.ts
index f11a0843f39..85afcfd793f 100644
--- a/src/Graph.ts
+++ b/src/Graph.ts
@@ -1,4 +1,4 @@
-import * as acorn from 'fork-acorn-optional-chaining';
+import * as acorn from 'acorn';
 import GlobalScope from './ast/scopes/GlobalScope';
 import { PathTracker } from './ast/utils/PathTracker';
 import Chunk from './Chunk';
diff --git a/src/Module.ts b/src/Module.ts
index 941a5594d09..bf1788c8b01 100644
--- a/src/Module.ts
+++ b/src/Module.ts
@@ -1,4 +1,4 @@
-import * as acorn from 'fork-acorn-optional-chaining';
+import * as acorn from 'acorn';
 import { locate } from 'locate-character';
 import MagicString from 'magic-string';
 import extractAssignedNames from 'rollup-pluginutils/src/extractAssignedNames';
diff --git a/src/ModuleLoader.ts b/src/ModuleLoader.ts
index f5f71a3ea55..d51977e39c1 100644
--- a/src/ModuleLoader.ts
+++ b/src/ModuleLoader.ts
@@ -1,4 +1,4 @@
-import * as acorn from 'fork-acorn-optional-chaining';
+import * as acorn from 'acorn';
 import ExternalModule from './ExternalModule';
 import Graph from './Graph';
 import Module from './Module';
diff --git a/src/ast/nodes/CallExpression.ts b/src/ast/nodes/CallExpression.ts
index 8cf4a67d393..2bf7a1c5e4f 100644
--- a/src/ast/nodes/CallExpression.ts
+++ b/src/ast/nodes/CallExpression.ts
@@ -29,7 +29,7 @@ export default class CallExpression extends NodeBase implements DeoptimizableEnt
 	annotatedPure?: boolean;
 	arguments!: (ExpressionNode | SpreadElement)[];
 	callee!: ExpressionNode | Super;
-	optional?: boolean;
+	optional!: boolean;
 	type!: NodeType.tCallExpression;
 
 	private callOptions!: CallOptions;
diff --git a/src/ast/nodes/ChainExpression.ts b/src/ast/nodes/ChainExpression.ts
new file mode 100644
index 00000000000..77c8a021819
--- /dev/null
+++ b/src/ast/nodes/ChainExpression.ts
@@ -0,0 +1,9 @@
+import CallExpression from './CallExpression';
+import MemberExpression from './MemberExpression';
+import * as NodeType from './NodeType';
+import { NodeBase } from './shared/Node';
+
+export default class ChainExpression extends NodeBase {
+	expression!: CallExpression | MemberExpression;
+	type!: NodeType.tChainExpression;
+}
diff --git a/src/ast/nodes/MemberExpression.ts b/src/ast/nodes/MemberExpression.ts
index 11a4c3642ec..8d88d357ef3 100644
--- a/src/ast/nodes/MemberExpression.ts
+++ b/src/ast/nodes/MemberExpression.ts
@@ -73,7 +73,7 @@ function getStringFromPath(path: PathWithPositions): string {
 export default class MemberExpression extends NodeBase implements DeoptimizableEntity, PatternNode {
 	computed!: boolean;
 	object!: ExpressionNode | Super;
-	optional?: boolean;
+	optional!: boolean;
 	property!: ExpressionNode;
 	propertyKey!: ObjectPathKey | null;
 	type!: NodeType.tMemberExpression;
diff --git a/src/ast/nodes/NodeType.ts b/src/ast/nodes/NodeType.ts
index 894f007c29f..3f5c69a85eb 100644
--- a/src/ast/nodes/NodeType.ts
+++ b/src/ast/nodes/NodeType.ts
@@ -9,6 +9,7 @@ export type tBlockStatement = 'BlockStatement';
 export type tBreakStatement = 'BreakStatement';
 export type tCallExpression = 'CallExpression';
 export type tCatchClause = 'CatchClause';
+export type tChainExpression = 'ChainExpression';
 export type tClassBody = 'ClassBody';
 export type tClassDeclaration = 'ClassDeclaration';
 export type tClassExpression = 'ClassExpression';
@@ -78,6 +79,7 @@ export const BlockStatement: tBlockStatement = 'BlockStatement';
 export const BreakStatement: tBreakStatement = 'BreakStatement';
 export const CallExpression: tCallExpression = 'CallExpression';
 export const CatchClause: tCatchClause = 'CatchClause';
+export const ChainExpression: tChainExpression = 'ChainExpression';
 export const ClassBody: tClassBody = 'ClassBody';
 export const ClassDeclaration: tClassDeclaration = 'ClassDeclaration';
 export const ClassExpression: tClassExpression = 'ClassExpression';
diff --git a/src/ast/nodes/index.ts b/src/ast/nodes/index.ts
index 3b7ecc5fc96..c5642b92499 100644
--- a/src/ast/nodes/index.ts
+++ b/src/ast/nodes/index.ts
@@ -9,6 +9,7 @@ import BlockStatement from './BlockStatement';
 import BreakStatement from './BreakStatement';
 import CallExpression from './CallExpression';
 import CatchClause from './CatchClause';
+import ChainExpression from './ChainExpression';
 import ClassBody from './ClassBody';
 import ClassDeclaration from './ClassDeclaration';
 import ClassExpression from './ClassExpression';
@@ -82,6 +83,7 @@ export const nodeConstructors: {
 	BreakStatement,
 	CallExpression,
 	CatchClause,
+	ChainExpression,
 	ClassBody,
 	ClassDeclaration,
 	ClassExpression,
diff --git a/src/utils/options/normalizeInputOptions.ts b/src/utils/options/normalizeInputOptions.ts
index 152477a1417..1086b942ef3 100644
--- a/src/utils/options/normalizeInputOptions.ts
+++ b/src/utils/options/normalizeInputOptions.ts
@@ -1,5 +1,4 @@
 import injectClassFields from 'acorn-class-fields';
-import injectImportMeta from 'acorn-import-meta';
 import injectStaticClassFeatures from 'acorn-static-class-features';
 import {
 	ExternalOption,
@@ -114,7 +113,6 @@ const getAcorn = (config: GenericConfigObject): acorn.Options => ({
 });
 
 const getAcornInjectPlugins = (config: GenericConfigObject): Function[] => [
-	injectImportMeta,
 	injectClassFields,
 	injectStaticClassFeatures,
 	...(ensureArray(config.acornInjectPlugins) as any)
diff --git a/src/utils/pureComments.ts b/src/utils/pureComments.ts
index e2f52165b49..c45336a4520 100644
--- a/src/utils/pureComments.ts
+++ b/src/utils/pureComments.ts
@@ -1,6 +1,6 @@
+import * as acorn from 'acorn';
 // @ts-ignore
 import { base as basicWalker } from 'acorn-walk';
-import * as acorn from 'fork-acorn-optional-chaining';
 import { CommentDescription } from '../Module';
 
 // patch up acorn-walk until class-fields are officially supported
diff --git a/test/function/samples/options-hook/_config.js b/test/function/samples/options-hook/_config.js
index 230a403ca1d..6b30e1daccc 100644
--- a/test/function/samples/options-hook/_config.js
+++ b/test/function/samples/options-hook/_config.js
@@ -15,7 +15,7 @@ module.exports = {
 						preserveParens: false,
 						sourceType: 'module'
 					},
-					acornInjectPlugins: [null, null, null],
+					acornInjectPlugins: [null, null],
 					context: 'undefined',
 					experimentalCacheExpiry: 10,
 					inlineDynamicImports: false,