diff --git a/ios/LocalizationModule.swift b/ios/LocalizationModule.swift
index 7c5d59b..6334633 100644
--- a/ios/LocalizationModule.swift
+++ b/ios/LocalizationModule.swift
@@ -112,6 +112,8 @@ public final class LocalizationModule: Module {
       return "roc"
     case .iso8601:
       return "iso8601"
+    @unknown default:
+      return String(describing: calendar.identifier)
     }
   }