diff --git a/src/compiler/factory.ts b/src/compiler/factory.ts
index 65c1c92f366..a566a432791 100644
--- a/src/compiler/factory.ts
+++ b/src/compiler/factory.ts
@@ -1982,7 +1982,7 @@ namespace ts {
         node.decorators = asNodeArray(decorators);
         node.modifiers = asNodeArray(modifiers);
         node.isExportEquals = isExportEquals;
-        node.expression = expression;
+        node.expression = isExportEquals ? parenthesizeBinaryOperand(SyntaxKind.EqualsToken, expression, /*isLeftSideOfBinary*/ false, /*leftOperand*/ undefined) : parenthesizeDefaultExpression(expression);
         return node;
     }
 
@@ -3885,6 +3885,27 @@ namespace ts {
             : e;
     }
 
+    /**
+     *  [Per the spec](https://tc39.github.io/ecma262/#prod-ExportDeclaration), `export default` accepts _AssigmentExpression_ but
+     *  has a lookahead restriction for `function`, `async function`, and `class`.
+     *
+     * Basically, that means we need to parenthesize in the following cases:
+     *
+     * - BinaryExpression of CommaToken
+     * - CommaList (synthetic list of multiple comma expressions)
+     * - FunctionExpression
+     * - ClassExpression
+     */
+    export function parenthesizeDefaultExpression(e: Expression) {
+        const check = skipPartiallyEmittedExpressions(e);
+        return (check.kind === SyntaxKind.ClassExpression ||
+            check.kind === SyntaxKind.FunctionExpression ||
+            check.kind === SyntaxKind.CommaListExpression ||
+            isBinaryExpression(check) && check.operatorToken.kind === SyntaxKind.CommaToken)
+            ? createParen(e)
+            : e;
+    }
+
     /**
      * Wraps an expression in parentheses if it is needed in order to use the expression
      * as the expression of a NewExpression node.
diff --git a/tests/baselines/reference/exportDefaultParenthesize.js b/tests/baselines/reference/exportDefaultParenthesize.js
new file mode 100644
index 00000000000..31fe9b6da3e
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultParenthesize.js
@@ -0,0 +1,72 @@
+//// [tests/cases/compiler/exportDefaultParenthesize.ts] ////
+
+//// [commalist.ts]
+export default {
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+};
+
+//// [comma.ts]
+export default {
+    ['foo']: 42
+};
+
+//// [functionexpression.ts]
+export default () => 42;
+
+
+//// [commalist.js]
+export default (_a = {},
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a['foo' + ''] = 42,
+    _a);
+var _a;
+//// [comma.js]
+export default (_a = {},
+    _a['foo'] = 42,
+    _a);
+var _a;
+//// [functionexpression.js]
+export default (function () { return 42; });
diff --git a/tests/baselines/reference/exportDefaultParenthesize.symbols b/tests/baselines/reference/exportDefaultParenthesize.symbols
new file mode 100644
index 00000000000..684138ebb3b
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultParenthesize.symbols
@@ -0,0 +1,38 @@
+=== tests/cases/compiler/commalist.ts ===
+export default {
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.    ['foo'+'']: 42,
+No type information for this code.};
+No type information for this code.
+No type information for this code.=== tests/cases/compiler/comma.ts ===
+export default {
+    ['foo']: 42
+>'foo' : Symbol(['foo'], Decl(comma.ts, 0, 16))
+
+};
+
+=== tests/cases/compiler/functionexpression.ts ===
+export default () => 42;
+No type information for this code.
+No type information for this code.
\ No newline at end of file
diff --git a/tests/baselines/reference/exportDefaultParenthesize.types b/tests/baselines/reference/exportDefaultParenthesize.types
new file mode 100644
index 00000000000..43e016a9ea0
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultParenthesize.types
@@ -0,0 +1,159 @@
+=== tests/cases/compiler/commalist.ts ===
+export default {
+>{    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,    ['foo'+'']: 42,} : { [x: string]: number; }
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+    ['foo'+'']: 42,
+>'foo'+'' : string
+>'foo' : "foo"
+>'' : ""
+>42 : 42
+
+};
+
+=== tests/cases/compiler/comma.ts ===
+export default {
+>{    ['foo']: 42} : { ['foo']: number; }
+
+    ['foo']: 42
+>'foo' : "foo"
+>42 : 42
+
+};
+
+=== tests/cases/compiler/functionexpression.ts ===
+export default () => 42;
+>() => 42 : () => number
+>42 : 42
+
diff --git a/tests/baselines/reference/exportDefaultParenthesizeES6.js b/tests/baselines/reference/exportDefaultParenthesizeES6.js
new file mode 100644
index 00000000000..7d7d686e251
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultParenthesizeES6.js
@@ -0,0 +1,6 @@
+//// [classexpr.ts]
+export default (class Foo {} as any);
+
+//// [classexpr.js]
+export default (class Foo {
+});
diff --git a/tests/baselines/reference/exportDefaultParenthesizeES6.symbols b/tests/baselines/reference/exportDefaultParenthesizeES6.symbols
new file mode 100644
index 00000000000..bddaccade51
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultParenthesizeES6.symbols
@@ -0,0 +1,4 @@
+=== tests/cases/compiler/classexpr.ts ===
+export default (class Foo {} as any);
+>Foo : Symbol(Foo, Decl(classexpr.ts, 0, 16))
+
diff --git a/tests/baselines/reference/exportDefaultParenthesizeES6.types b/tests/baselines/reference/exportDefaultParenthesizeES6.types
new file mode 100644
index 00000000000..a2f76670b23
--- /dev/null
+++ b/tests/baselines/reference/exportDefaultParenthesizeES6.types
@@ -0,0 +1,7 @@
+=== tests/cases/compiler/classexpr.ts ===
+export default (class Foo {} as any);
+>(class Foo {} as any) : any
+>class Foo {} as any : any
+>class Foo {} : typeof Foo
+>Foo : typeof Foo
+
diff --git a/tests/baselines/reference/exportEqualsAmd.js b/tests/baselines/reference/exportEqualsAmd.js
index 8b66b8896e3..e76b9dbacc8 100644
--- a/tests/baselines/reference/exportEqualsAmd.js
+++ b/tests/baselines/reference/exportEqualsAmd.js
@@ -5,5 +5,5 @@ export = { ["hi"]: "there" };
 define(["require", "exports"], function (require, exports) {
     "use strict";
     var _a;
-    return _a = {}, _a["hi"] = "there", _a;
+    return (_a = {}, _a["hi"] = "there", _a);
 });
diff --git a/tests/baselines/reference/exportEqualsUmd.js b/tests/baselines/reference/exportEqualsUmd.js
index 2201f2b8407..1d8a99717ed 100644
--- a/tests/baselines/reference/exportEqualsUmd.js
+++ b/tests/baselines/reference/exportEqualsUmd.js
@@ -13,5 +13,5 @@ export = { ["hi"]: "there" };
 })(function (require, exports) {
     "use strict";
     var _a;
-    return _a = {}, _a["hi"] = "there", _a;
+    return (_a = {}, _a["hi"] = "there", _a);
 });
diff --git a/tests/cases/compiler/exportDefaultParenthesize.ts b/tests/cases/compiler/exportDefaultParenthesize.ts
new file mode 100644
index 00000000000..8303eea0234
--- /dev/null
+++ b/tests/cases/compiler/exportDefaultParenthesize.ts
@@ -0,0 +1,36 @@
+// @target: es5
+// @module: esnext
+// @filename: commalist.ts
+export default {
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+    ['foo'+'']: 42,
+};
+
+// @filename: comma.ts
+export default {
+    ['foo']: 42
+};
+
+// @filename: functionexpression.ts
+export default () => 42;
diff --git a/tests/cases/compiler/exportDefaultParenthesizeES6.ts b/tests/cases/compiler/exportDefaultParenthesizeES6.ts
new file mode 100644
index 00000000000..20d1a10cc4c
--- /dev/null
+++ b/tests/cases/compiler/exportDefaultParenthesizeES6.ts
@@ -0,0 +1,4 @@
+// @target: es6
+// @module: esnext
+// @filename: classexpr.ts
+export default (class Foo {} as any);
\ No newline at end of file