diff --git a/src/file/settings/settings.ts b/src/file/settings/settings.ts
index 7801ed8fe5..e63d539a39 100644
--- a/src/file/settings/settings.ts
+++ b/src/file/settings/settings.ts
@@ -47,7 +47,7 @@ export class SettingsAttributes extends XmlAttributeComponent<ISettingsAttribute
 }
 
 export interface ISettingsOptions {
-    compatabilityModeVersion?: number;
+    readonly compatabilityModeVersion?: number;
 }
 
 export class Settings extends XmlComponent {