diff --git a/AsyncDisplayKit/ASCollectionView.h b/AsyncDisplayKit/ASCollectionView.h
index fb28fa5eb3..9e560cc662 100644
--- a/AsyncDisplayKit/ASCollectionView.h
+++ b/AsyncDisplayKit/ASCollectionView.h
@@ -143,8 +143,10 @@
  */
 - (ASCellNode *)collectionView:(ASCollectionView *)collectionView nodeForItemAtIndexPath:(NSIndexPath *)indexPath;
 
+@optional
+
 /**
- * Indicator to lock the data source for data fetching in asyn mode.
+ * Indicator to lock the data source for data fetching in async mode.
  * We should not update the data source until the data source has been unlocked. Otherwise, it will incur data inconsistence or exception
  * due to the data access in async mode.
  *
@@ -153,7 +155,7 @@
 - (void)collectionViewLockDataSource:(ASCollectionView *)collectionView;
 
 /**
- * Indicator to unlock the data source for data fetching in asyn mode.
+ * Indicator to unlock the data source for data fetching in async mode.
  * We should not update the data source until the data source has been unlocked. Otherwise, it will incur data inconsistence or exception
  * due to the data access in async mode.
  *
diff --git a/AsyncDisplayKit/ASCollectionView.mm b/AsyncDisplayKit/ASCollectionView.mm
index 256ae11038..e02c392bca 100644
--- a/AsyncDisplayKit/ASCollectionView.mm
+++ b/AsyncDisplayKit/ASCollectionView.mm
@@ -459,7 +459,7 @@ static BOOL _isInterceptedSelector(SEL sel)
 
 - (void)dataControllerUnlockDataSource
 {
-  ASDisplayNodeAssert(self.asyncDataSourceLocked, @"The data source has alredy been unlocked !");
+  ASDisplayNodeAssert(self.asyncDataSourceLocked, @"The data source has already been unlocked");
 
   self.asyncDataSourceLocked = NO;
   if ([_asyncDataSource respondsToSelector:@selector(collectionViewUnlockDataSource:)]) {
diff --git a/AsyncDisplayKit/ASTableView.h b/AsyncDisplayKit/ASTableView.h
index 930afbd80c..b5f60c3070 100644
--- a/AsyncDisplayKit/ASTableView.h
+++ b/AsyncDisplayKit/ASTableView.h
@@ -145,8 +145,10 @@
  */
 - (ASCellNode *)tableView:(ASTableView *)tableView nodeForRowAtIndexPath:(NSIndexPath *)indexPath;
 
+@optional
+
 /**
- * Indicator to lock the data source for data fetching in asyn mode.
+ * Indicator to lock the data source for data fetching in async mode.
  * We should not update the data source until the data source has been unlocked. Otherwise, it will incur data inconsistence or exception
  * due to the data access in async mode.
  *
diff --git a/AsyncDisplayKit/ASTableView.mm b/AsyncDisplayKit/ASTableView.mm
index d34886576b..5e7ecf249f 100644
--- a/AsyncDisplayKit/ASTableView.mm
+++ b/AsyncDisplayKit/ASTableView.mm
@@ -498,7 +498,7 @@ static BOOL _isInterceptedSelector(SEL sel)
 
 - (void)dataControllerLockDataSource
 {
-  ASDisplayNodeAssert(!self.asyncDataSourceLocked, @"The data source has already been locked !");
+  ASDisplayNodeAssert(!self.asyncDataSourceLocked, @"The data source has already been locked");
 
   self.asyncDataSourceLocked = YES;
 
@@ -509,7 +509,7 @@ static BOOL _isInterceptedSelector(SEL sel)
 
 - (void)dataControllerUnlockDataSource
 {
-  ASDisplayNodeAssert(self.asyncDataSourceLocked, @"The data source has already been unlocked !");
+  ASDisplayNodeAssert(self.asyncDataSourceLocked, @"The data source has already been unlocked");
 
   self.asyncDataSourceLocked = NO;