diff --git a/main.ts b/main.ts
index 1fb78b3..28803fb 100644
--- a/main.ts
+++ b/main.ts
@@ -6,6 +6,7 @@ import {
   IsIn,
   IsNotEmptyObject,
   IsString,
+  MaxLength,
   validate,
 } from "class-validator"
 import { js2xml } from "xml-js"
@@ -34,6 +35,14 @@ export async function generateKlc(
     throw new Error(errors.map((e) => e.toString()).join(", "))
   }
 
+  const windowsErrors = await validate(
+    plainToClass(WindowsAttributes, layout.os.windows)
+  )
+
+  if (windowsErrors.length) {
+    throw new Error(windowsErrors.map((e) => e.toString()).join(", "))
+  }
+
   const klcLocales = {
     Thai: "th-TH",
   }
@@ -435,5 +444,19 @@ export class Layout {
 }
 
 interface OSAttributes {
-  windows: { company: string; localeId: string; installerName: string }
+  windows: WindowsAttributes
+}
+
+class WindowsAttributes {
+  @IsString()
+  company: string
+
+  @IsString()
+  localeId: string
+
+  @IsString()
+  @MaxLength(8, {
+    message: "Installer name cannot be longer than 8 characters",
+  })
+  installerName: string
 }