diff --git a/AFNetworking/AFURLConnectionOperation.h b/AFNetworking/AFURLConnectionOperation.h
index 14d0226..4eaee7f 100644
--- a/AFNetworking/AFURLConnectionOperation.h
+++ b/AFNetworking/AFURLConnectionOperation.h
@@ -75,7 +75,7 @@ extern NSString * const AFNetworkingOperationDidFinishNotification;
  
  @warning Attempting to load a `file://` URL in iOS 4 may result in an `NSInvalidArgumentException`, caused by the connection returning `NSURLResponse` rather than `NSHTTPURLResponse`, which is the behavior as of iOS 5.
  */
-@interface AFURLConnectionOperation : NSOperation {
+@interface AFURLConnectionOperation : NSOperation <NSURLConnectionDataDelegate> {
 @private
     unsigned short _state;
     BOOL _cancelled;