diff --git a/AsyncDisplayKit/Details/ASImageProtocols.h b/AsyncDisplayKit/Details/ASImageProtocols.h
index 2235dafe17..8a235083ca 100644
--- a/AsyncDisplayKit/Details/ASImageProtocols.h
+++ b/AsyncDisplayKit/Details/ASImageProtocols.h
@@ -43,13 +43,11 @@ NS_ASSUME_NONNULL_BEGIN
   @param completion The block to be invoked when the download has completed, or has failed.
   @param image The image that was downloaded, if the image could be successfully downloaded; nil otherwise.
   @param error An error describing why the download of `URL` failed, if the download failed; nil otherwise.
-  @discussion If `URL` is nil, `completion` will be invoked immediately with a nil image and an error describing why the 
-      download failed. This method is likely to be called on the main thread, so any custom implementations should make
-      sure to background any expensive download operations.
+  @discussion This method is likely to be called on the main thread, so any custom implementations should make sure to background any expensive download operations.
   @result An opaque identifier to be used in canceling the download, via `cancelImageDownloadForIdentifier:`. You must 
       retain the identifier if you wish to use it later.
  */
-- (id)downloadImageWithURL:(nullable NSURL *)URL
+- (id)downloadImageWithURL:(NSURL *)URL
              callbackQueue:(nullable dispatch_queue_t)callbackQueue
      downloadProgressBlock:(void (^ _Nullable)(CGFloat progress))downloadProgressBlock
                 completion:(void (^ _Nullable)(CGImageRef _Nullable image, NSError * _Nullable error))completion;