diff --git a/SDWebImage/Core/SDWebImageDownloader.m b/SDWebImage/Core/SDWebImageDownloader.m
index 33bb937f..777349b2 100644
--- a/SDWebImage/Core/SDWebImageDownloader.m
+++ b/SDWebImage/Core/SDWebImageDownloader.m
@@ -556,8 +556,8 @@ didReceiveResponse:(NSURLResponse *)response
     self = [super init];
     if (self) {
         _downloadOperation = downloadOperation;
-        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(downloadDidReceiveResponse:) name:SDWebImageDownloadReceiveResponseNotification object:downloadOperation];
-        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(downloadDidStop:) name:SDWebImageDownloadStopNotification object:downloadOperation];
+        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(downloadDidReceiveResponse:) name:SDWebImageDownloadReceiveResponseNotification object:nil];
+        [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(downloadDidStop:) name:SDWebImageDownloadStopNotification object:nil];
     }
     return self;
 }