diff --git a/XCDYouTubeKit/XCDYouTubeClient.h b/XCDYouTubeKit/XCDYouTubeClient.h
index 3e3a29fc..09b5e67f 100644
--- a/XCDYouTubeKit/XCDYouTubeClient.h
+++ b/XCDYouTubeKit/XCDYouTubeClient.h
@@ -124,7 +124,7 @@ NS_ASSUME_NONNULL_BEGIN
  *
  *  @return A newly initialized`<XCDYouTubeVideoQueryOperation>` object for canceling the asynchronous query  operation. If you call the `cancel` method before the operation is finished, the completion handler will not be called.
  */
-- (XCDYouTubeVideoQueryOperation *) queryVideo:(XCDYouTubeVideo *)video cookies:(nullable NSArray <NSHTTPCookie *>*)cookies completionHandler:(void (^)(NSDictionary *streamURLs, NSError * __nullable error, NSDictionary<id, NSError *> *streamErrors))completionHandler;
+- (XCDYouTubeVideoQueryOperation *) queryVideo:(XCDYouTubeVideo *)video cookies:(nullable NSArray <NSHTTPCookie *>*)cookies completionHandler:(void (^)(NSDictionary * __nullable streamURLs, NSError * __nullable error, NSDictionary<id, NSError *> * __nullable streamErrors))completionHandler;
 
 @end
 
diff --git a/XCDYouTubeKit/XCDYouTubeClient.m b/XCDYouTubeKit/XCDYouTubeClient.m
index 80475590..a0e75b3d 100644
--- a/XCDYouTubeKit/XCDYouTubeClient.m
+++ b/XCDYouTubeKit/XCDYouTubeClient.m
@@ -86,7 +86,7 @@ - (instancetype) initWithLanguageIdentifier:(NSString *)languageIdentifier
 	return [self getVideoWithIdentifier:videoIdentifier cookies:cookies customPatterns:nil  completionHandler:completionHandler];
 }
 
-- (XCDYouTubeVideoQueryOperation *) queryVideo:(XCDYouTubeVideo *)video cookies:(NSArray<NSHTTPCookie *> *)cookies completionHandler:(void (^)(NSDictionary * _Nonnull, NSError * _Nullable, NSDictionary<id, NSError *> *streamErrors))completionHandler
+- (XCDYouTubeVideoQueryOperation *)queryVideo:(XCDYouTubeVideo *)video cookies:(NSArray<NSHTTPCookie *> *)cookies completionHandler:(void (^)(NSDictionary * _Nullable, NSError * _Nullable, NSDictionary<id,NSError *> * _Nullable))completionHandler
 {
 	if (!completionHandler)
 		@throw [NSException exceptionWithName:NSInvalidArgumentException reason:@"The `completionHandler` argument must not be nil." userInfo:nil];
diff --git a/XCDYouTubeKit/XCDYouTubeVideoQueryOperation.h b/XCDYouTubeKit/XCDYouTubeVideoQueryOperation.h
index 0317e3d1..917218b8 100644
--- a/XCDYouTubeKit/XCDYouTubeVideoQueryOperation.h
+++ b/XCDYouTubeKit/XCDYouTubeVideoQueryOperation.h
@@ -36,9 +36,9 @@ NS_ASSUME_NONNULL_BEGIN
 
 /// A dictionary of video stream URLs that are reachable. The keys are the YouTube [itag](https://en.wikipedia.org/wiki/YouTube#Quality_and_formats) values as `NSNumber` objects. The values are the video URLs as `NSURL` objects. There is also the special `XCDYouTubeVideoQualityHTTPLiveStreaming` key for live videos.
 #if __has_feature(objc_generics)
-@property (atomic, readonly) NSDictionary<id, NSURL *> *streamURLs;
+@property (atomic, readonly, nullable) NSDictionary<id, NSURL *> *streamURLs;
 #else
-@property (atomic, readonly) NSDictionary *streamURLs;
+@property (atomic, readonly, nullable) NSDictionary *streamURLs;
 #endif
 
 /// Returns an error of the `XCDYouTubeVideoErrorDomain` domain if the operation failed or nil if it succeeded. The operation will only return an error if no stream URL is reachable (error code: `XCDYouTubeErrorNoStreamAvailable`). Also, this returns `nil` if the operation is not yet finished or if it was canceled.