diff --git a/RxSwift/Schedulers/SerialDispatchQueueScheduler.swift b/RxSwift/Schedulers/SerialDispatchQueueScheduler.swift
index 82e83e3b..4108fe43 100644
--- a/RxSwift/Schedulers/SerialDispatchQueueScheduler.swift
+++ b/RxSwift/Schedulers/SerialDispatchQueueScheduler.swift
@@ -12,7 +12,7 @@ import Foundation
 Abstracts the work that needs to be performed on a specific `dispatch_queue_t`. It will make sure 
 that even if concurrent dispatch queue is passed, it's transformed into a serial one.
 
-It is extemely important that this scheduler is serial, because
+It is extremely important that this scheduler is serial, because
 certain operator perform optimizations that rely on that property.
 
 Because there is no way of detecting is passed dispatch queue serial or