diff --git a/SDWebImage/SDWebImageDownloaderOperation.m b/SDWebImage/SDWebImageDownloaderOperation.m
index df8db73..1dbc069 100644
--- a/SDWebImage/SDWebImageDownloaderOperation.m
+++ b/SDWebImage/SDWebImageDownloaderOperation.m
@@ -21,7 +21,7 @@
 @property (assign, nonatomic) long long expectedSize;
 @property (strong, nonatomic) NSMutableData *imageData;
 @property (strong, nonatomic) NSURLConnection *connection;
-@property (assign, nonatomic) dispatch_queue_t queue;
+@property (SDDispatchQueueSetterSementics, nonatomic) dispatch_queue_t queue;
 
 @end