         } else if value == nil {
             remove(key)
         } else {
-            assertionFailure("Invalid value type")
+            assertionFailure("Invalid value type, needs to be a NSCoding-compliant type")
         }
     }
     

@available(*, deprecated=1, message="Please migrate to static keys to use this.")
public postfix func ++ (proxy: NSUserDefaults.Proxy) {
    proxy += 1
}
        if let value: AnyObject = value as? AnyObject {
            set(key, NSKeyedArchiver.archivedDataWithRootObject(value))
        } else {
            assertionFailure("Invalid value type, needs to be a NSCoding-compliant type")
        }
    }
    
