diff --git a/SDWebImage/SDWebImageDownloader.m b/SDWebImage/SDWebImageDownloader.m
index 09ceb4f9..251bc513 100644
--- a/SDWebImage/SDWebImageDownloader.m
+++ b/SDWebImage/SDWebImageDownloader.m
@@ -127,8 +127,8 @@ static NSString *const kCompletedCallbackKey = @"completed";
         operation = [[SDWebImageDownloaderOperation alloc] initWithRequest:request
                                                                    options:options
                                                                   progress:^(NSInteger receivedSize, NSInteger expectedSize) {
-                                                                      if (!wself) return;
                                                                       SDWebImageDownloader *sself = wself;
+                                                                      if (!sself) return;
                                                                       NSArray *callbacksForURL = [sself callbacksForURL:url];
                                                                       for (NSDictionary *callbacks in callbacksForURL) {
                                                                           SDWebImageDownloaderProgressBlock callback = callbacks[kProgressCallbackKey];
@@ -136,8 +136,8 @@ static NSString *const kCompletedCallbackKey = @"completed";
                                                                       }
                                                                   }
                                                                  completed:^(UIImage *image, NSData *data, NSError *error, BOOL finished) {
-                                                                     if (!wself) return;
                                                                      SDWebImageDownloader *sself = wself;
+                                                                     if (!sself) return;
                                                                      NSArray *callbacksForURL = [sself callbacksForURL:url];
                                                                      if (finished) {
                                                                          [sself removeCallbacksForURL:url];
@@ -148,8 +148,8 @@ static NSString *const kCompletedCallbackKey = @"completed";
                                                                      }
                                                                  }
                                                                  cancelled:^{
-                                                                     if (!wself) return;
                                                                      SDWebImageDownloader *sself = wself;
+                                                                     if (!sself) return;
                                                                      [sself removeCallbacksForURL:url];
                                                                  }];
         
diff --git a/SDWebImage/SDWebImagePrefetcher.h b/SDWebImage/SDWebImagePrefetcher.h
index af33db4e..5664ac5c 100644
--- a/SDWebImage/SDWebImagePrefetcher.h
+++ b/SDWebImage/SDWebImagePrefetcher.h
@@ -20,15 +20,15 @@
  *
  * @param imagePrefetcher The current image prefetcher
  * @param imageURL The image url that was prefetched
- * @param finishedCount The total number of images that were prefetched
- * @param totalCount The total number of images that need to be prefetched
+ * @param finishedCount The total number of images that were prefetched (successful or not)
+ * @param totalCount The total number of images that were to be prefetched
  */
 - (void)imagePrefetcher:(SDWebImagePrefetcher *)imagePrefetcher didPrefetchURL:(NSURL *)imageURL finishedCount:(NSUInteger)finishedCount totalCount:(NSUInteger)totalCount;
 
 /**
  * Called when all images are prefetched.
  * @param imagePrefetcher The current image prefetcher
- * @param totalCount The total number of images that need to be prefetched
+ * @param totalCount The total number of images that were prefetched (whether successful or not)
  * @param skippedCount The total number of images that were skipped
  */
 - (void)imagePrefetcher:(SDWebImagePrefetcher *)imagePrefetcher didFinishWithTotalCount:(NSUInteger)totalCount skippedCount:(NSUInteger)skippedCount;
@@ -78,7 +78,7 @@
  * and skips images for failed downloads and proceed to the next image in the list
  *
  * @param urls list of URLs to prefetch
- * @param progressBlock block to be called when progress updates
+ * @param progressBlock block to be called when progress updates; first parameter is the number of completed (successful or not) requests, second parameter is the total number of images originally requested to be prefetched
  * @param completionBlock block to be called when prefetching is completed
  */
 - (void)prefetchURLs:(NSArray *)urls progress:(void (^)(NSUInteger, NSUInteger))progressBlock completed:(void (^)(NSUInteger, NSUInteger))completionBlock;
diff --git a/SDWebImage/SDWebImagePrefetcher.m b/SDWebImage/SDWebImagePrefetcher.m
index 74a3bc1e..8c4bc2f9 100644
--- a/SDWebImage/SDWebImagePrefetcher.m
+++ b/SDWebImage/SDWebImagePrefetcher.m
@@ -88,7 +88,7 @@
                 [self startPrefetchingAtIndex:self.requestedCount];
             });
         }
-        else if (self.finishedCount + self.skippedCount == self.requestedCount) {
+        else if (self.finishedCount == self.requestedCount) {
             [self reportStatus];
             if (self.completionBlock) {
                 self.completionBlock(self.finishedCount, self.skippedCount);