diff --git a/Observable/Classes/Lock.swift b/Observable/Classes/Lock.swift
deleted file mode 100644
index 1d0f0ca..0000000
--- a/Observable/Classes/Lock.swift
+++ /dev/null
@@ -1,11 +0,0 @@
-import Foundation
-
-// https://cocoawithlove.com/blog/2016/06/02/threads-and-mutexes.html
-// http://www.vadimbulavin.com/atomic-properties/
-// https://stackoverflow.com/a/47345863/976628
-internal protocol Lock {
-    func lock()
-    func unlock()
-}
-
-extension NSRecursiveLock: Lock {}
diff --git a/Observable/Classes/Observable.swift b/Observable/Classes/Observable.swift
index 48f89d4..fa0202c 100644
--- a/Observable/Classes/Observable.swift
+++ b/Observable/Classes/Observable.swift
@@ -10,7 +10,7 @@ public class Observable<T> {
     private var observers: [Int: (Observer, DispatchQueue?)] = [:]
     private var uniqueID = (0...).makeIterator()
     
-    fileprivate let lock: Lock = NSRecursiveLock()
+    fileprivate let lock = NSRecursiveLock()
     
     fileprivate var _value: T {
         didSet {