diff --git a/SDWebImage/SDWebImageDownloader.m b/SDWebImage/SDWebImageDownloader.m
index a7eef36e..ec67b5bd 100644
--- a/SDWebImage/SDWebImageDownloader.m
+++ b/SDWebImage/SDWebImageDownloader.m
@@ -25,7 +25,7 @@ static void * SDWebImageDownloaderContext = &SDWebImageDownloaderContext;
 
 - (nonnull instancetype)init NS_UNAVAILABLE;
 + (nonnull instancetype)new  NS_UNAVAILABLE;
-- (nonnull instancetype)initWithDownloadOperation:(nullable NSOperation<SDWebImageDownloaderOperation> *)downloadOperation NS_DESIGNATED_INITIALIZER;
+- (nonnull instancetype)initWithDownloadOperation:(nullable NSOperation<SDWebImageDownloaderOperation> *)downloadOperation;
 
 @end