diff --git a/SDWebImage/SDWebImageManager.h b/SDWebImage/SDWebImageManager.h
index cae25d31..9a630a71 100644
--- a/SDWebImage/SDWebImageManager.h
+++ b/SDWebImage/SDWebImageManager.h
@@ -166,7 +166,7 @@ SDWebImageManager *manager = [SDWebImageManager sharedManager];
 
  * @endcode
  */
-@property (copy) SDWebImageCacheKeyFilterBlock cacheKeyFilter;
+@property (nonatomic, copy) SDWebImageCacheKeyFilterBlock cacheKeyFilter;
 
 /**
  * Returns global SDWebImageManager instance.