diff --git a/src/parser.ts b/src/parser.ts
index fe21966ec..78369e027 100644
--- a/src/parser.ts
+++ b/src/parser.ts
@@ -516,7 +516,10 @@ export class Parser {
             op === '>>>=' ||
             op === '&=' ||
             op === '^=' ||
-            op === '|=';
+            op === '|=' ||
+            op === '&&=' ||
+            op === '||=' ||
+            op === '??=';
     }
 
     // Cover grammar support.
diff --git a/src/scanner.ts b/src/scanner.ts
index 2a746e029..59a392f52 100644
--- a/src/scanner.ts
+++ b/src/scanner.ts
@@ -613,7 +613,12 @@ export class Scanner {
                 ++this.index;
                 if (this.source[this.index] === '?') {
                     ++this.index;
-                    str = '??';
+                    if (this.source[this.index] === '=') {
+                        ++this.index;
+                        str = '??=';
+                    } else {
+                        str = '??';
+                    }
                 } if (this.source[this.index] === '.' && !/^\d$/.test(this.source[this.index + 1])) {
                     // "?." in "foo?.3:0" should not be treated as optional chaining.
                     // See https://github.com/tc39/proposal-optional-chaining#notes
@@ -642,13 +647,14 @@ export class Scanner {
                     // 3-character punctuators.
                     str = str.substr(0, 3);
                     if (str === '===' || str === '!==' || str === '>>>' ||
-                        str === '<<=' || str === '>>=' || str === '**=') {
+                        str === '<<=' || str === '>>=' || str === '**=' ||
+                        str === '&&=' || str === '||=') {
                         this.index += 3;
                     } else {
 
                         // 2-character punctuators.
                         str = str.substr(0, 2);
-                        if (str === '&&' || str === '||' || str === '??' ||
+                        if (str === '&&' || str === '||' ||
                             str === '==' || str === '!=' ||
                             str === '+=' || str === '-=' || str === '*=' || str === '/=' ||
                             str === '++' || str === '--' ||
diff --git a/test/fixtures/es2021/logical-assignment/logical-and-assignment.js b/test/fixtures/es2021/logical-assignment/logical-and-assignment.js
new file mode 100644
index 000000000..6d65d0624
--- /dev/null
+++ b/test/fixtures/es2021/logical-assignment/logical-and-assignment.js
@@ -0,0 +1 @@
+foo &&= true
\ No newline at end of file
diff --git a/test/fixtures/es2021/logical-assignment/logical-and-assignment.tree.json b/test/fixtures/es2021/logical-assignment/logical-and-assignment.tree.json
new file mode 100644
index 000000000..183791eaa
--- /dev/null
+++ b/test/fixtures/es2021/logical-assignment/logical-and-assignment.tree.json
@@ -0,0 +1,148 @@
+{
+    "type": "Program",
+    "body": [
+        {
+            "type": "ExpressionStatement",
+            "expression": {
+                "type": "AssignmentExpression",
+                "operator": "&&=",
+                "left": {
+                    "type": "Identifier",
+                    "name": "foo",
+                    "range": [
+                        0,
+                        3
+                    ],
+                    "loc": {
+                        "start": {
+                            "line": 1,
+                            "column": 0
+                        },
+                        "end": {
+                            "line": 1,
+                            "column": 3
+                        }
+                    }
+                },
+                "right": {
+                    "type": "Literal",
+                    "value": true,
+                    "raw": "true",
+                    "range": [
+                        8,
+                        12
+                    ],
+                    "loc": {
+                        "start": {
+                            "line": 1,
+                            "column": 8
+                        },
+                        "end": {
+                            "line": 1,
+                            "column": 12
+                        }
+                    }
+                },
+                "range": [
+                    0,
+                    12
+                ],
+                "loc": {
+                    "start": {
+                        "line": 1,
+                        "column": 0
+                    },
+                    "end": {
+                        "line": 1,
+                        "column": 12
+                    }
+                }
+            },
+            "range": [
+                0,
+                12
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 0
+                },
+                "end": {
+                    "line": 1,
+                    "column": 12
+                }
+            }
+        }
+    ],
+    "sourceType": "script",
+    "range": [
+        0,
+        12
+    ],
+    "loc": {
+        "start": {
+            "line": 1,
+            "column": 0
+        },
+        "end": {
+            "line": 1,
+            "column": 12
+        }
+    },
+    "tokens": [
+        {
+            "type": "Identifier",
+            "value": "foo",
+            "range": [
+                0,
+                3
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 0
+                },
+                "end": {
+                    "line": 1,
+                    "column": 3
+                }
+            }
+        },
+        {
+            "type": "Punctuator",
+            "value": "&&=",
+            "range": [
+                4,
+                7
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 4
+                },
+                "end": {
+                    "line": 1,
+                    "column": 7
+                }
+            }
+        },
+        {
+            "type": "Boolean",
+            "value": "true",
+            "range": [
+                8,
+                12
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 8
+                },
+                "end": {
+                    "line": 1,
+                    "column": 12
+                }
+            }
+        }
+    ]
+}
\ No newline at end of file
diff --git a/test/fixtures/es2021/logical-assignment/nullish-coalescing-assignment.js b/test/fixtures/es2021/logical-assignment/nullish-coalescing-assignment.js
new file mode 100644
index 000000000..2698ecc30
--- /dev/null
+++ b/test/fixtures/es2021/logical-assignment/nullish-coalescing-assignment.js
@@ -0,0 +1 @@
+foo ??= true
\ No newline at end of file
diff --git a/test/fixtures/es2021/logical-assignment/nullish-coalescing-assignment.tree.json b/test/fixtures/es2021/logical-assignment/nullish-coalescing-assignment.tree.json
new file mode 100644
index 000000000..b56db6ac9
--- /dev/null
+++ b/test/fixtures/es2021/logical-assignment/nullish-coalescing-assignment.tree.json
@@ -0,0 +1,148 @@
+{
+    "type": "Program",
+    "body": [
+        {
+            "type": "ExpressionStatement",
+            "expression": {
+                "type": "AssignmentExpression",
+                "operator": "??=",
+                "left": {
+                    "type": "Identifier",
+                    "name": "foo",
+                    "range": [
+                        0,
+                        3
+                    ],
+                    "loc": {
+                        "start": {
+                            "line": 1,
+                            "column": 0
+                        },
+                        "end": {
+                            "line": 1,
+                            "column": 3
+                        }
+                    }
+                },
+                "right": {
+                    "type": "Literal",
+                    "value": true,
+                    "raw": "true",
+                    "range": [
+                        8,
+                        12
+                    ],
+                    "loc": {
+                        "start": {
+                            "line": 1,
+                            "column": 8
+                        },
+                        "end": {
+                            "line": 1,
+                            "column": 12
+                        }
+                    }
+                },
+                "range": [
+                    0,
+                    12
+                ],
+                "loc": {
+                    "start": {
+                        "line": 1,
+                        "column": 0
+                    },
+                    "end": {
+                        "line": 1,
+                        "column": 12
+                    }
+                }
+            },
+            "range": [
+                0,
+                12
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 0
+                },
+                "end": {
+                    "line": 1,
+                    "column": 12
+                }
+            }
+        }
+    ],
+    "sourceType": "script",
+    "range": [
+        0,
+        12
+    ],
+    "loc": {
+        "start": {
+            "line": 1,
+            "column": 0
+        },
+        "end": {
+            "line": 1,
+            "column": 12
+        }
+    },
+    "tokens": [
+        {
+            "type": "Identifier",
+            "value": "foo",
+            "range": [
+                0,
+                3
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 0
+                },
+                "end": {
+                    "line": 1,
+                    "column": 3
+                }
+            }
+        },
+        {
+            "type": "Punctuator",
+            "value": "??=",
+            "range": [
+                4,
+                7
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 4
+                },
+                "end": {
+                    "line": 1,
+                    "column": 7
+                }
+            }
+        },
+        {
+            "type": "Boolean",
+            "value": "true",
+            "range": [
+                8,
+                12
+            ],
+            "loc": {
+                "start": {
+                    "line": 1,
+                    "column": 8
+                },
+                "end": {
+                    "line": 1,
+                    "column": 12
+                }
+            }
+        }
+    ]
+}
\ No newline at end of file
diff --git a/test/test-262-whitelist.txt b/test/test-262-whitelist.txt
index d1bb4ad5e..2bc45046f 100644
--- a/test/test-262-whitelist.txt
+++ b/test/test-262-whitelist.txt
@@ -15310,20 +15310,12 @@ test/language/expressions/async-generator/yield-thenable-create-resolving-functi
 test/language/expressions/async-generator/yield-thenable-create-resolving-functions-resolve.js(strict mode)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-assignment-expression-coalesce.js(default)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-assignment-expression-coalesce.js(strict mode)
-test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-assignment-expression-logical-and.js(default)
-test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-assignment-expression-logical-and.js(strict mode)
-test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-assignment-expression-logical-or.js(default)
-test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-await-expression.js(default)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-await-expression.js(strict mode)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-integer-separators.js(default)
 test/language/expressions/class/cpn-class-expr-accessors-computed-property-name-from-integer-separators.js(strict mode)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-coalesce.js(default)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-coalesce.js(strict mode)
-test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-logical-and.js(default)
-test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-logical-and.js(strict mode)
-test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-logical-or.js(default)
-test/language/expressions/class/cpn-class-expr-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-await-expression.js(default)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-await-expression.js(strict mode)
 test/language/expressions/class/cpn-class-expr-computed-property-name-from-integer-separators.js(default)
@@ -15534,28 +15526,6 @@ test/language/expressions/class/private-static-setter-multiple-evaluations-of-cl
 test/language/expressions/class/private-static-setter-multiple-evaluations-of-class-factory.js(strict mode)
 test/language/expressions/logical-assignment/lgcl-and-assignment-operator-bigint.js(default)
 test/language/expressions/logical-assignment/lgcl-and-assignment-operator-bigint.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-lhs-before-rhs.js(default)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-lhs-before-rhs.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-namedevaluation-arrow-function.js(default)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-namedevaluation-arrow-function.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-namedevaluation-class-expression.js(default)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-namedevaluation-class-expression.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-namedevaluation-function.js(default)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-namedevaluation-function.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-no-set-put.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-no-set.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-non-extensible.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-non-writeable-put.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-non-writeable.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-unresolved-lhs.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-unresolved-rhs-put.js(default)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-unresolved-rhs-put.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-unresolved-rhs.js(default)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator-unresolved-rhs.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator.js(default)
-test/language/expressions/logical-assignment/lgcl-and-assignment-operator.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-and-whitespace.js(default)
-test/language/expressions/logical-assignment/lgcl-and-whitespace.js(strict mode)
 test/language/expressions/logical-assignment/lgcl-nullish-assignment-operator-bigint.js(default)
 test/language/expressions/logical-assignment/lgcl-nullish-assignment-operator-bigint.js(strict mode)
 test/language/expressions/logical-assignment/lgcl-nullish-assignment-operator-lhs-before-rhs.js(default)
@@ -15582,28 +15552,6 @@ test/language/expressions/logical-assignment/lgcl-nullish-whitespace.js(default)
 test/language/expressions/logical-assignment/lgcl-nullish-whitespace.js(strict mode)
 test/language/expressions/logical-assignment/lgcl-or-assignment-operator-bigint.js(default)
 test/language/expressions/logical-assignment/lgcl-or-assignment-operator-bigint.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-lhs-before-rhs.js(default)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-lhs-before-rhs.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-namedevaluation-arrow-function.js(default)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-namedevaluation-arrow-function.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-namedevaluation-class-expression.js(default)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-namedevaluation-class-expression.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-namedevaluation-function.js(default)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-namedevaluation-function.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-no-set-put.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-no-set.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-non-extensible.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-non-writeable-put.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-non-writeable.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-unresolved-lhs.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-unresolved-rhs-put.js(default)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-unresolved-rhs-put.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-unresolved-rhs.js(default)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator-unresolved-rhs.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator.js(default)
-test/language/expressions/logical-assignment/lgcl-or-assignment-operator.js(strict mode)
-test/language/expressions/logical-assignment/lgcl-or-whitespace.js(default)
-test/language/expressions/logical-assignment/lgcl-or-whitespace.js(strict mode)
 test/language/expressions/object/__proto__-permitted-dup.js(default)
 test/language/expressions/object/__proto__-permitted-dup.js(strict mode)
 test/language/expressions/object/covered-ident-name-prop-name-literal-break-escaped.js(default)
@@ -15680,10 +15628,6 @@ test/language/expressions/object/covered-ident-name-prop-name-literal-with-escap
 test/language/expressions/object/covered-ident-name-prop-name-literal-with-escaped.js(strict mode)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignment-expression-coalesce.js(default)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignment-expression-coalesce.js(strict mode)
-test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignment-expression-logical-and.js(default)
-test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignment-expression-logical-and.js(strict mode)
-test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignment-expression-logical-or.js(default)
-test/language/expressions/object/cpn-obj-lit-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-await-expression.js(default)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-await-expression.js(strict mode)
 test/language/expressions/object/cpn-obj-lit-computed-property-name-from-integer-separators.js(default)
@@ -15885,20 +15829,12 @@ test/language/statements/async-generator/yield-star-return-missing-value-is-awai
 test/language/statements/async-generator/yield-star-return-missing-value-is-awaited.js(strict mode)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-assignment-expression-coalesce.js(default)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-assignment-expression-coalesce.js(strict mode)
-test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-assignment-expression-logical-and.js(default)
-test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-assignment-expression-logical-and.js(strict mode)
-test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-assignment-expression-logical-or.js(default)
-test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-await-expression.js(default)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-await-expression.js(strict mode)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-integer-separators.js(default)
 test/language/statements/class/cpn-class-decl-accessors-computed-property-name-from-integer-separators.js(strict mode)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-coalesce.js(default)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-coalesce.js(strict mode)
-test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-logical-and.js(default)
-test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-logical-and.js(strict mode)
-test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-logical-or.js(default)
-test/language/statements/class/cpn-class-decl-computed-property-name-from-assignment-expression-logical-or.js(strict mode)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-await-expression.js(default)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-await-expression.js(strict mode)
 test/language/statements/class/cpn-class-decl-computed-property-name-from-integer-separators.js(default)
@@ -16101,12 +16037,8 @@ test/language/statements/class/ident-name-method-def-with-escaped.js(default)
 test/language/statements/class/ident-name-method-def-with-escaped.js(strict mode)
 test/language/statements/switch/scope-lex-async-generator.js(default)
 test/language/statements/switch/scope-lex-async-generator.js(strict mode)
-test/annexB/language/expressions/logical-assignment/emulates-undefined-and.js(default)
-test/annexB/language/expressions/logical-assignment/emulates-undefined-and.js(strict mode)
 test/annexB/language/expressions/logical-assignment/emulates-undefined-coalesce.js(default)
 test/annexB/language/expressions/logical-assignment/emulates-undefined-coalesce.js(strict mode)
-test/annexB/language/expressions/logical-assignment/emulates-undefined-or.js(default)
-test/annexB/language/expressions/logical-assignment/emulates-undefined-or.js(strict mode)
 test/built-ins/Atomics/add/bigint/non-shared-bufferdata.js(default)
 test/built-ins/Atomics/add/bigint/non-shared-bufferdata.js(strict mode)
 test/built-ins/Atomics/and/bigint/non-shared-bufferdata.js(default)