diff --git a/crates/oxc_ast/src/ast/ts.rs b/crates/oxc_ast/src/ast/ts.rs
index 339f8948e..f53b4c56f 100644
--- a/crates/oxc_ast/src/ast/ts.rs
+++ b/crates/oxc_ast/src/ast/ts.rs
@@ -861,6 +861,10 @@ pub enum TSModuleDeclarationName<'a> {
 }
 
 impl<'a> TSModuleDeclarationName<'a> {
+    pub fn is_string_literal(&self) -> bool {
+        matches!(self, Self::StringLiteral(_))
+    }
+
     pub fn name(&self) -> &Atom<'a> {
         match self {
             Self::Identifier(ident) => &ident.name,
diff --git a/crates/oxc_transformer/src/typescript/diagnostics.rs b/crates/oxc_transformer/src/typescript/diagnostics.rs
index 9989d051e..381bf515f 100644
--- a/crates/oxc_transformer/src/typescript/diagnostics.rs
+++ b/crates/oxc_transformer/src/typescript/diagnostics.rs
@@ -10,3 +10,8 @@ pub fn export_assignment_unsupported(span0: Span) -> OxcDiagnostic {
     OxcDiagnostic::warning("`export = <value>;` is only supported when compiling modules to CommonJS.\nPlease consider using `export default <value>;`, or add @babel/plugin-transform-modules-commonjs to your Babel config.")
 .with_labels([span0.into()])
 }
+
+pub fn ambient_module_nested(span0: Span) -> OxcDiagnostic {
+    OxcDiagnostic::warning("Ambient modules cannot be nested in other modules or namespaces.")
+        .with_label(span0)
+}
diff --git a/crates/oxc_transformer/src/typescript/namespace.rs b/crates/oxc_transformer/src/typescript/namespace.rs
index 7cddfae5e..14cc23eb7 100644
--- a/crates/oxc_transformer/src/typescript/namespace.rs
+++ b/crates/oxc_transformer/src/typescript/namespace.rs
@@ -1,6 +1,6 @@
 use rustc_hash::FxHashSet;
 
-use super::TypeScript;
+use super::{diagnostics::ambient_module_nested, TypeScript};
 
 use oxc_allocator::{Box, Vec};
 use oxc_ast::{ast::*, syntax_directed_operations::BoundNames};
@@ -121,6 +121,7 @@ impl<'a> TypeScript<'a> {
         parent_export: Option<Expression<'a>>,
     ) -> Option<Statement<'a>> {
         let mut names: FxHashSet<Atom<'a>> = FxHashSet::default();
+
         let real_name = decl.id.name();
 
         let name = self.ctx.ast.new_atom(&format!("_{}", real_name.clone())); // path.scope.generateUid(realName.name);
@@ -155,6 +156,10 @@ impl<'a> TypeScript<'a> {
         for stmt in namespace_top_level {
             match stmt {
                 Statement::TSModuleDeclaration(decl) => {
+                    if decl.id.is_string_literal() {
+                        self.ctx.error(ambient_module_nested(decl.span));
+                    }
+
                     let module_name = decl.id.name().clone();
                     if let Some(transformed) = self.handle_nested(decl.unbox(), None) {
                         is_empty = false;
@@ -218,6 +223,10 @@ impl<'a> TypeScript<'a> {
                                 new_stmts.extend(stmts);
                             }
                             Declaration::TSModuleDeclaration(module_decl) => {
+                                if module_decl.id.is_string_literal() {
+                                    self.ctx.error(ambient_module_nested(module_decl.span));
+                                }
+
                                 let module_name = module_decl.id.name().clone();
                                 if let Some(transformed) = self.handle_nested(
                                     module_decl.unbox(),
diff --git a/tasks/transform_conformance/babel.snap.md b/tasks/transform_conformance/babel.snap.md
index 1d368d2a8..1b2f6cb72 100644
--- a/tasks/transform_conformance/babel.snap.md
+++ b/tasks/transform_conformance/babel.snap.md
@@ -1,4 +1,4 @@
-Passed: 304/362
+Passed: 306/362
 
 # All Passed:
 * babel-preset-react
@@ -24,7 +24,7 @@ Passed: 304/362
 * opts/optimizeConstEnums/input.ts
 * opts/rewriteImportExtensions/input.ts
 
-# babel-plugin-transform-typescript (119/156)
+# babel-plugin-transform-typescript (121/156)
 * class/accessor-allowDeclareFields-false/input.ts
 * class/accessor-allowDeclareFields-true/input.ts
 * enum/mix-references/input.ts
@@ -34,8 +34,6 @@ Passed: 304/362
 * exports/export-type-star-from/input.ts
 * imports/enum-value/input.ts
 * imports/type-only-export-specifier-2/input.ts
-* namespace/ambient-module-nested/input.ts
-* namespace/ambient-module-nested-exported/input.ts
 * namespace/canonical/input.ts
 * namespace/contentious-names/input.ts
 * namespace/empty-removed/input.ts