                     let key = DefaultsKey<Serializable?>("test", defaultValue: self.defaultValue)
 
                     var update: DefaultsObserver<Serializable?>.Update?
-                    let observer = defaults.observe(key, options: [.initial, .old, .new]) { receivedUpdate in
+                    observer = defaults.observe(key, options: [.initial, .old, .new]) { receivedUpdate in
                         update = receivedUpdate
                     }
 

        #if !os(Linux)
        given("key-value observing") {
            var defaults: DefaultsAdapter<FrogKeyStore<Serializable>>!

            beforeEach {
                let suiteName = UUID().uuidString

                    defaults[key: key] = self.customValue

                    var update: DefaultsObserver<Serializable?>.Update?
                    observer = defaults.observe(key, options: [.initial, .old, .new]) { receivedUpdate in
                        update = receivedUpdate
                    }

