diff --git a/crates/oxc_linter/src/rules/typescript/no_namespace.rs b/crates/oxc_linter/src/rules/typescript/no_namespace.rs
index 3f5ddb9d9a48a..42b19b5029129 100644
--- a/crates/oxc_linter/src/rules/typescript/no_namespace.rs
+++ b/crates/oxc_linter/src/rules/typescript/no_namespace.rs
@@ -133,7 +133,6 @@ impl Rule for NoNamespace {
         }
     }
 
-    #[expect(clippy::cast_possible_truncation)]
     fn run<'a>(&self, node: &AstNode<'a>, ctx: &LintContext<'a>) {
         let AstKind::TSModuleDeclaration(declaration) = node.kind() else {
             return;
@@ -156,16 +155,14 @@ impl Rule for NoNamespace {
             return;
         }
 
-        let declaration_code = declaration.span.source_text(ctx.source_text());
-
         let span = match declaration.kind {
             TSModuleDeclarationKind::Global => None, // handled above
-            TSModuleDeclarationKind::Module => declaration_code
-                .find("module")
-                .map(|i| Span::sized(declaration.span.start + i as u32, 6)),
-            TSModuleDeclarationKind::Namespace => declaration_code
-                .find("namespace")
-                .map(|i| Span::sized(declaration.span.start + i as u32, 9)),
+            TSModuleDeclarationKind::Module => ctx
+                .find_next_token_from(declaration.span.start, "module")
+                .map(|i| Span::sized(declaration.span.start + i, 6)),
+            TSModuleDeclarationKind::Namespace => ctx
+                .find_next_token_from(declaration.span.start, "namespace")
+                .map(|i| Span::sized(declaration.span.start + i, 9)),
         };
         if let Some(span) = span {
             ctx.diagnostic(no_namespace_diagnostic(span));
@@ -381,6 +378,8 @@ fn test() {
     		 }",
             Some(serde_json::json!([{ "allowDeclarations": true }])),
         ),
+        ("declare /* module */ module foo {}", None),
+        ("declare /* namespace */ namespace foo {}", None),
     ];
 
     Tester::new(NoNamespace::NAME, NoNamespace::PLUGIN, pass, fail).test_and_snapshot();
diff --git a/crates/oxc_linter/src/snapshots/typescript_no_namespace.snap b/crates/oxc_linter/src/snapshots/typescript_no_namespace.snap
index 4fd99011135b0..7471ee3418335 100644
--- a/crates/oxc_linter/src/snapshots/typescript_no_namespace.snap
+++ b/crates/oxc_linter/src/snapshots/typescript_no_namespace.snap
@@ -276,3 +276,17 @@ source: crates/oxc_linter/src/tester.rs
  3 │                  export declare namespace C {}
    ╰────
   help: Replace the namespace with an ES2015 module or use `declare module`
+
+  ⚠ typescript-eslint(no-namespace): ES2015 module syntax is preferred over namespaces.
+   ╭─[no_namespace.tsx:1:22]
+ 1 │ declare /* module */ module foo {}
+   ·                      ──────
+   ╰────
+  help: Replace the namespace with an ES2015 module or use `declare module`
+
+  ⚠ typescript-eslint(no-namespace): ES2015 module syntax is preferred over namespaces.
+   ╭─[no_namespace.tsx:1:25]
+ 1 │ declare /* namespace */ namespace foo {}
+   ·                         ─────────
+   ╰────
+  help: Replace the namespace with an ES2015 module or use `declare module`