diff --git a/RxSwift/Observables/Implementations/Filter.swift b/RxSwift/Observables/Implementations/Filter.swift
index b78fafb3..9adb0b28 100644
--- a/RxSwift/Observables/Implementations/Filter.swift
+++ b/RxSwift/Observables/Implementations/Filter.swift
@@ -12,8 +12,6 @@ class FilterSink<O : ObserverType>: Sink<O>, ObserverType {
     typealias Predicate = (Element) throws -> Bool
     typealias Element = O.E
     
-    typealias Parent = Filter<Element>
-    
     private let _predicate: Predicate
     
     init(predicate: Predicate, observer: O) {