diff --git a/AsyncDisplayKit/ASCollectionViewProtocols.h b/AsyncDisplayKit/ASCollectionViewProtocols.h
index 0f0b5ed7c6..5c4bcf96ed 100644
--- a/AsyncDisplayKit/ASCollectionViewProtocols.h
+++ b/AsyncDisplayKit/ASCollectionViewProtocols.h
@@ -6,6 +6,8 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
+NS_ASSUME_NONNULL_BEGIN
+
 /**
  * This is a subset of UICollectionViewDataSource.
  *
@@ -50,7 +52,9 @@
 - (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath;
 
 - (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(NSIndexPath *)indexPath;
-- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender;
-- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(id)sender;
+- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender;
+- (void)collectionView:(UICollectionView *)collectionView performAction:(SEL)action forItemAtIndexPath:(NSIndexPath *)indexPath withSender:(nullable id)sender;
 
 @end
+
+NS_ASSUME_NONNULL_END