diff --git a/crates/oxc_linter/src/rules/typescript/no_misused_new.rs b/crates/oxc_linter/src/rules/typescript/no_misused_new.rs
index f1d068767bf6d..7de35e47da3c5 100644
--- a/crates/oxc_linter/src/rules/typescript/no_misused_new.rs
+++ b/crates/oxc_linter/src/rules/typescript/no_misused_new.rs
@@ -144,7 +144,7 @@ fn test() {
     use crate::tester::Tester;
 
     let pass = vec![
-        "declare abstract class C { foo() {} get new();bar();}",
+        "declare abstract class C { foo(); get new();bar();}",
         "class C { constructor();}",
         "const foo = class { constructor();};",
         "const foo = class { new(): X;};",
diff --git a/crates/oxc_parser/src/js/class.rs b/crates/oxc_parser/src/js/class.rs
index 3679a4d0f7ad9..106947adeb9bb 100644
--- a/crates/oxc_parser/src/js/class.rs
+++ b/crates/oxc_parser/src/js/class.rs
@@ -738,6 +738,12 @@ impl<'a> ParserImpl<'a> {
                 }
             }
         }
+
+        if self.ctx.has_ambient()
+            && let Some(body) = &method.value.body
+        {
+            self.error(diagnostics::implementation_in_ambient(Span::empty(body.span.start)));
+        }
     }
 
     fn check_method_definition_accessor(&mut self, method: &MethodDefinition<'a>) {
diff --git a/tasks/coverage/snapshots/parser_babel.snap b/tasks/coverage/snapshots/parser_babel.snap
index ea70d010bd5c6..f58b3ce43ebc7 100644
--- a/tasks/coverage/snapshots/parser_babel.snap
+++ b/tasks/coverage/snapshots/parser_babel.snap
@@ -176,6 +176,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
 
 Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/class/modifiers-override/input.ts
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/modifiers-override/input.ts:17:19]
+ 16 │ declare class DeclaredClass extends BaseClass {
+ 17 │   override test() {}
+    ·                   ▲
+ 18 │ }
+    ╰────
+
   × Identifier `show` has already been declared
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/modifiers-override/input.ts:2:12]
  1 │ class MyClass extends BaseClass {
@@ -12510,6 +12518,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Allowed modifiers are: private, protected, public, static, abstract, override, async
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/declare-method/input.ts:2:17]
+ 1 │ class A {
+ 2 │   declare foo() {}
+   ·                 ▲
+ 3 │ }
+   ╰────
+
   × Expected a semicolon or an implicit semicolon after a statement, but found none
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/declare-new-line-abstract/input.ts:1:8]
  1 │ declare abstract
@@ -12634,6 +12650,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Allowed modifiers are: private, protected, public, static, abstract, override, async
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/generator-method-with-modifiers/input.ts:7:16]
+ 6 │   readonly *e() {}
+ 7 │   declare *f() {}
+   ·                ▲
+ 8 │   protected *g() {}
+   ╰────
+
   × TS(1244): Abstract methods can only appear within an abstract class.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/generator-method-with-modifiers/input.ts:5:13]
  4 │   static *c() {}
@@ -12779,6 +12803,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
    ╰────
   help: Allowed modifiers are: private, protected, public, static, abstract, override, async
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/optional-generator-method-with-invalid-modifiers/input.ts:4:17]
+ 3 │   readonly *e?() { }
+ 4 │   declare *f?() { }
+   ·                 ▲
+ 5 │ }
+   ╰────
+
   × TS(1245): Method 'd?.d' cannot have an implementation because it is marked abstract.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/optional-generator-method-with-invalid-modifiers/input.ts:8:14]
  7 │ class A {
@@ -12805,6 +12837,14 @@ Expect to Parse: tasks/coverage/babel/packages/babel-parser/test/fixtures/typesc
     ╰────
   help: Allowed modifiers are: private, protected, public, static, abstract, override, async
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/optional-generator-method-with-invalid-modifiers/input.ts:10:22]
+  9 │   readonly *[e?.e]?() { }
+ 10 │   declare *[f?.f]?() { }
+    ·                      ▲
+ 11 │ }
+    ╰────
+
   × TS(1244): Abstract methods can only appear within an abstract class.
    ╭─[babel/packages/babel-parser/test/fixtures/typescript/class/optional-generator-method-with-invalid-modifiers/input.ts:2:13]
  1 │ class C {
diff --git a/tasks/coverage/snapshots/parser_misc.snap b/tasks/coverage/snapshots/parser_misc.snap
index 19ae5da191b5d..b5b3e012711b5 100644
--- a/tasks/coverage/snapshots/parser_misc.snap
+++ b/tasks/coverage/snapshots/parser_misc.snap
@@ -733,6 +733,14 @@ Negative Passed: 134/134 (100.00%)
    ╰────
   help: Allowed modifiers are: private, protected, public, static, abstract, override, async
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[misc/fail/oxc-11713-24.ts:2:20]
+ 1 │ class Foo {
+ 2 │   declare method() {}
+   ·                    ▲
+ 3 │ }
+   ╰────
+
   × TS(1024): 'readonly' modifier can only appear on a property declaration or index signature.
    ╭─[misc/fail/oxc-11713-25.ts:2:3]
  1 │ class Foo {
diff --git a/tasks/coverage/snapshots/parser_typescript.snap b/tasks/coverage/snapshots/parser_typescript.snap
index 8e6e1ee2daabe..0206324945140 100644
--- a/tasks/coverage/snapshots/parser_typescript.snap
+++ b/tasks/coverage/snapshots/parser_typescript.snap
@@ -3,7 +3,7 @@ commit: 7f6a8467
 parser_typescript Summary:
 AST Parsed     : 9842/9843 (99.99%)
 Positive Passed: 9837/9843 (99.94%)
-Negative Passed: 1500/2555 (58.71%)
+Negative Passed: 1510/2555 (59.10%)
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration3.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDeclaration4.ts
@@ -14,8 +14,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/FunctionDecl
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/accessorInferredReturnTypeErrorInReturnStatement.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/accessorsInAmbientContext.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/allowSyntheticDefaultImports10.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ambientEnum1.ts
@@ -28,8 +26,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ambientExter
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ambientExternalModuleWithRelativeModuleName.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ambientGetters.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/ambientStatement1.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/amdDependencyCommentName4.ts
@@ -182,8 +178,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/constantEnum
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/constructorOverloads3.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/constructorOverloads6.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/constructorOverloads7.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/constructorsWithSpecializedSignatures.ts
@@ -362,8 +356,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/exportAssign
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/exportDeclarationsInAmbientNamespaces2.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/exportDeclareClass1.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/exportDefaultAlias_excludesEverything.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/exportDefaultClassAndValue.ts
@@ -410,8 +402,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/extendedInte
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/externSemantics.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/externSyntax.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/externalModuleImmutableBindings.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/externalModuleRefernceResolutionOrderInImportDeclaration.ts
@@ -630,8 +620,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/mergedDeclar
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/mergedDeclarations3.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/methodInAmbientClass1.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/missingDomElement_UsingDomLib.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/compiler/missingDomElements.ts
@@ -1466,8 +1454,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalM
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/importsImplicitlyReadonly.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/initializersInDeclarations.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/multipleExportDefault1.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/externalModules/multipleExportDefault2.ts
@@ -1738,10 +1724,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ec
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors3.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors5.ts
-
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors6.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserGetAccessorWithTypeParameters1.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserSetAccessorWithTypeAnnotation1.ts
@@ -1752,8 +1734,6 @@ Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ec
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/ClassDeclarations/parserClassDeclaration12.ts
 
-Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/ClassDeclarations/parserClassDeclaration18.ts
-
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/ClassDeclarations/parserClassDeclaration7.ts
 
 Expect Syntax Error: tasks/coverage/typescript/tests/cases/conformance/parser/ecmascript5/ComputedPropertyNames/parserES5ComputedPropertyName4.ts
@@ -2524,6 +2504,70 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ╰────
   help: Add a function body (`{}`).
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:3:17]
+ 2 │     class C {
+ 3 │         get X() { return 1; }
+   ·                 ▲
+ 4 │         set X(v) { }
+   ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:4:18]
+ 3 │         get X() { return 1; }
+ 4 │         set X(v) { }
+   ·                  ▲
+ 5 │ 
+   ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:6:24]
+ 5 │ 
+ 6 │         static get Y() { return 1; }
+   ·                        ▲
+ 7 │         static set Y(v) { }
+   ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:7:25]
+ 6 │         static get Y() { return 1; }
+ 7 │         static set Y(v) { }
+   ·                         ▲
+ 8 │     }
+   ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:12:13]
+ 11 │ declare class C {
+ 12 │     get X() { return 1; }
+    ·             ▲
+ 13 │     set X(v) { }
+    ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:13:14]
+ 12 │     get X() { return 1; }
+ 13 │     set X(v) { }
+    ·              ▲
+ 14 │ 
+    ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:15:20]
+ 14 │ 
+ 15 │     static get Y() { return 1; }
+    ·                    ▲
+ 16 │     static set Y(v) { }
+    ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/compiler/accessorsInAmbientContext.ts:16:21]
+ 15 │     static get Y() { return 1; }
+ 16 │     static set Y(v) { }
+    ·                     ▲
+ 17 │ }
+    ╰────
+
   × Unexpected token
     ╭─[typescript/tests/cases/compiler/aliasErrors.ts:13:12]
  12 │ import m2 = no.mod;
@@ -2572,6 +2616,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  5 │     }
    ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/ambientGetters.ts:6:18]
+ 5 │ declare class B {
+ 6 │     get length() { return 0; }
+   ·                  ▲
+ 7 │ }
+   ╰────
+
   × Expected `;` but found `:`
    ╭─[typescript/tests/cases/compiler/ambientPropertyDeclarationInJs.ts:6:17]
  5 │ 
@@ -4518,6 +4570,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  8 │ 
    ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/constructorOverloads6.ts:4:25]
+ 3 │     constructor(n: number);
+ 4 │     constructor(x: any) {
+   ·                         ▲
+ 5 │ 
+   ╰────
+
   × Multiple constructor implementations are not allowed.
    ╭─[typescript/tests/cases/compiler/constructorOverloads8.ts:2:5]
  1 │ class C {
@@ -5992,6 +6052,22 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  14 │ }
     ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/exportDeclareClass1.ts:2:21]
+ 1 │     export declare class eaC {
+ 2 │         static tF() { };
+   ·                     ▲
+ 3 │         static tsF(param:any) { };
+   ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/exportDeclareClass1.ts:3:31]
+ 2 │         static tF() { };
+ 3 │         static tsF(param:any) { };
+   ·                               ▲
+ 4 │     };
+   ╰────
+
   × Cannot use `await` as an identifier in an async context
    ╭─[typescript/tests/cases/compiler/exportDefaultAsyncFunction2.ts:2:17]
  1 │ export function async<T>(...args: any[]): any { }
@@ -6104,6 +6180,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ╰────
   help: Try inserting a semicolon here
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/externSyntax.ts:8:20]
+ 7 │         public f();
+ 8 │         public g() { } // error body
+   ·                    ▲
+ 9 │     }
+   ╰────
+
   × Expected `,` or `)` but found `=>`
    ╭─[typescript/tests/cases/compiler/fatarrowfunctionsErrors.ts:2:8]
  1 │ foo((...Far:any[])=>{return 0;})
@@ -7788,6 +7872,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  2 │ const b = !@#!@#!@#!
    ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/compiler/methodInAmbientClass1.ts:2:20]
+ 1 │     declare class Foo {
+ 2 │         fn(): boolean {
+   ·                       ▲
+ 3 │         }
+   ╰────
+
   × Identifier `baz` has already been declared
    ╭─[typescript/tests/cases/compiler/mismatchedClassConstructorVariable.ts:1:5]
  1 │ var baz: foo;
@@ -12238,6 +12330,30 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  21 │ 
     ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/conformance/ambient/ambientErrors.ts:39:23]
+ 38 │         y = 4;
+ 39 │         constructor() { }
+    ·                       ▲
+ 40 │         fn() { }
+    ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/conformance/ambient/ambientErrors.ts:40:14]
+ 39 │         constructor() { }
+ 40 │         fn() { }
+    ·              ▲
+ 41 │         static sfn() { }
+    ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/conformance/ambient/ambientErrors.ts:41:22]
+ 40 │         fn() { }
+ 41 │         static sfn() { }
+    ·                      ▲
+ 42 │     }
+    ╰────
+
   × TS(2309): An export assignment cannot be used in a module with other exported elements
     ╭─[typescript/tests/cases/conformance/ambient/ambientErrors.ts:57:5]
  56 │     export var q;
@@ -12788,6 +12904,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  9 │ }
    ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractDeclarations.d.ts:2:28]
+ 1 │ declare abstract class A {
+ 2 │     abstract constructor() {}
+   ·                            ▲
+ 3 │ }
+   ╰────
+
   × TS(1242): 'abstract' modifier can only appear on a class, method, or property declaration.
    ╭─[typescript/tests/cases/conformance/classes/classDeclarations/classAbstractKeyword/classAbstractDeclarations.d.ts:2:14]
  1 │ declare abstract class A {
@@ -15105,6 +15229,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
     ╰────
   help: Allowed modifiers are: private, protected, public, static, abstract, override, async
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+    ╭─[typescript/tests/cases/conformance/classes/propertyMemberDeclarations/derivedUninitializedPropertyDeclaration.ts:15:17]
+ 14 │ class BOther extends A {
+ 15 │     declare m() { return 2 } // not allowed on methods
+    ·                 ▲
+ 16 │     declare nonce: any; // ok, even though it's not in the base
+    ╰────
+
   × TS(2391): Function implementation is missing or not immediately following the declaration.
    ╭─[typescript/tests/cases/conformance/classes/propertyMemberDeclarations/memberFunctionDeclarations/memberFunctionOverloadMixingStaticAndInstance.ts:3:12]
  2 │     foo();
@@ -19675,6 +19807,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ·                      ─
    ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/conformance/externalModules/initializersInDeclarations.ts:6:16]
+ 5 │     "some prop" = 42;
+ 6 │     fn(): boolean {
+   ·                   ▲
+ 7 │         return false;
+   ╰────
+
   × Expected `as` but found `from`
    ╭─[typescript/tests/cases/conformance/externalModules/invalidSyntaxNamespaceImportWithAMD.ts:1:10]
  1 │ import * from Zero from "./0"
@@ -21146,6 +21286,22 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ╰────
   help: No modifiers are allowed here.
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors5.ts:2:13]
+ 1 │ declare class C {
+ 2 │   get foo() { return 0; }
+   ·             ▲
+ 3 │ }
+   ╰────
+
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors6.ts:2:14]
+ 1 │ declare class C {
+ 2 │   set foo(v) { }
+   ·              ▲
+ 3 │ }
+   ╰────
+
   × A 'get' accessor must not have any formal parameters.
    ╭─[typescript/tests/cases/conformance/parser/ecmascript5/Accessors/parserAccessors7.ts:1:18]
  1 │ var v = { get foo(v: number) { } };
@@ -21294,6 +21450,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
  3 │    constructor() { }
    ╰────
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/conformance/parser/ecmascript5/ClassDeclarations/parserClassDeclaration18.ts:4:25]
+ 3 │     constructor(n: number);
+ 4 │     constructor(x: any) {
+   ·                         ▲
+ 5 │     }
+   ╰────
+
   × TS(1175): 'implements' clause already seen
    ╭─[typescript/tests/cases/conformance/parser/ecmascript5/ClassDeclarations/parserClassDeclaration2.ts:1:9]
  1 │ class C implements A implements B {
@@ -22590,6 +22754,14 @@ Expect to Parse: tasks/coverage/typescript/tests/cases/conformance/statements/Va
    ╰────
   help: Allowed modifiers are: private, protected, public, static, abstract, override, async
 
+  × TS(1183): An implementation cannot be declared in ambient contexts.
+   ╭─[typescript/tests/cases/conformance/parser/ecmascript5/MemberFunctionDeclarations/parserMemberFunctionDeclaration5.ts:2:19]
+ 1 │ class C {
+ 2 │     declare Foo() { }
+   ·                   ▲
+ 3 │ }
+   ╰────
+
   × Identifier `public` has already been declared
    ╭─[typescript/tests/cases/conformance/parser/ecmascript5/MemberFunctionDeclarations/parserMemberFunctionDeclarationAmbiguities1.ts:2:3]
  1 │ class C {
diff --git a/tasks/coverage/snapshots/semantic_babel.snap b/tasks/coverage/snapshots/semantic_babel.snap
index 6bace7e0ffe46..d2fbe00c95c77 100644
--- a/tasks/coverage/snapshots/semantic_babel.snap
+++ b/tasks/coverage/snapshots/semantic_babel.snap
@@ -367,6 +367,7 @@ Function implementation is missing or not immediately following the declaration.
 Function implementation is missing or not immediately following the declaration.
 
 semantic Error: tasks/coverage/babel/packages/babel-parser/test/fixtures/typescript/class/modifiers-override/input.ts
+An implementation cannot be declared in ambient contexts.
 Identifier `show` has already been declared
 Identifier `size` has already been declared