diff --git a/AFNetworking/AFURLConnectionOperation.h b/AFNetworking/AFURLConnectionOperation.h
index ab08518..358b57a 100644
--- a/AFNetworking/AFURLConnectionOperation.h
+++ b/AFNetworking/AFURLConnectionOperation.h
@@ -216,7 +216,7 @@ extern NSString * const AFNetworkingOperationDidFinishNotification;
  
  @see setDownloadProgressBlock
  */
-- (void)setUploadProgressBlock:(void (^)(NSInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToWrite))block;
+- (void)setUploadProgressBlock:(void (^)(NSUInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToWrite))block;
 
 /**
  Sets a callback to be called when an undetermined number of bytes have been downloaded from the server.
@@ -225,7 +225,7 @@ extern NSString * const AFNetworkingOperationDidFinishNotification;
   
  @see setUploadProgressBlock
  */
-- (void)setDownloadProgressBlock:(void (^)(NSInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead))block;
+- (void)setDownloadProgressBlock:(void (^)(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead))block;
 
 ///-------------------------------------------------
 /// @name Setting NSURLConnection Delegate Callbacks
diff --git a/AFNetworking/AFURLConnectionOperation.m b/AFNetworking/AFURLConnectionOperation.m
index ad462a4..98a0343 100644
--- a/AFNetworking/AFURLConnectionOperation.m
+++ b/AFNetworking/AFURLConnectionOperation.m
@@ -47,7 +47,7 @@ NSString * const AFNetworkingErrorDomain = @"com.alamofire.networking.error";
 NSString * const AFNetworkingOperationDidStartNotification = @"com.alamofire.networking.operation.start";
 NSString * const AFNetworkingOperationDidFinishNotification = @"com.alamofire.networking.operation.finish";
 
-typedef void (^AFURLConnectionOperationProgressBlock)(NSInteger bytes, long long totalBytes, long long totalBytesExpected);
+typedef void (^AFURLConnectionOperationProgressBlock)(NSUInteger bytes, long long totalBytes, long long totalBytesExpected);
 typedef BOOL (^AFURLConnectionOperationAuthenticationAgainstProtectionSpaceBlock)(NSURLConnection *connection, NSURLProtectionSpace *protectionSpace);
 typedef void (^AFURLConnectionOperationAuthenticationChallengeBlock)(NSURLConnection *connection, NSURLAuthenticationChallenge *challenge);
 typedef NSCachedURLResponse * (^AFURLConnectionOperationCacheResponseBlock)(NSURLConnection *connection, NSCachedURLResponse *cachedResponse);
@@ -287,11 +287,11 @@ static inline BOOL AFStateTransitionIsValid(AFOperationState fromState, AFOperat
 }
 #endif
 
-- (void)setUploadProgressBlock:(void (^)(NSInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToWrite))block {
+- (void)setUploadProgressBlock:(void (^)(NSUInteger bytesWritten, long long totalBytesWritten, long long totalBytesExpectedToWrite))block {
     self.uploadProgress = block;
 }
 
-- (void)setDownloadProgressBlock:(void (^)(NSInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead))block {
+- (void)setDownloadProgressBlock:(void (^)(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead))block {
     self.downloadProgress = block;
 }
 
@@ -563,7 +563,7 @@ didReceiveResponse:(NSURLResponse *)response
     
     if (self.downloadProgress) {
         dispatch_async(dispatch_get_main_queue(), ^{
-            self.downloadProgress((long long)[data length], self.totalBytesRead, self.response.expectedContentLength);
+            self.downloadProgress([data length], self.totalBytesRead, self.response.expectedContentLength);
         });
     }
 }