diff --git a/AsyncDisplayKit/ASCellNode.h b/AsyncDisplayKit/ASCellNode.h
index 50cdcbab9f..e6b5a6ae9f 100644
--- a/AsyncDisplayKit/ASCellNode.h
+++ b/AsyncDisplayKit/ASCellNode.h
@@ -120,7 +120,7 @@ typedef NS_ENUM(NSUInteger, ASCellNodeVisibilityEvent) {
  */
 - (instancetype)initWithViewControllerBlock:(ASDisplayNodeViewControllerBlock)viewControllerBlock didLoadBlock:(nullable ASDisplayNodeDidLoadBlock)didLoadBlock;
 
-- (void)cellNodeVisibilityEvent:(ASCellNodeVisibilityEvent)event inScrollView:(UIScrollView *)scrollView withCellFrame:(CGRect)cellFrame;
+- (void)cellNodeVisibilityEvent:(ASCellNodeVisibilityEvent)event inScrollView:(nullable UIScrollView *)scrollView withCellFrame:(CGRect)cellFrame;
 
 @end
 
diff --git a/AsyncDisplayKit/ASCollectionView.mm b/AsyncDisplayKit/ASCollectionView.mm
index 0657caa0b5..1fba98796b 100644
--- a/AsyncDisplayKit/ASCollectionView.mm
+++ b/AsyncDisplayKit/ASCollectionView.mm
@@ -721,9 +721,10 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 
 - (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
 {
+  CGPoint contentOffset = scrollView.contentOffset;
   _deceleratingVelocity = CGPointMake(
-    scrollView.contentOffset.x - ((targetContentOffset != NULL) ? targetContentOffset->x : 0),
-    scrollView.contentOffset.y - ((targetContentOffset != NULL) ? targetContentOffset->y : 0)
+    contentOffset.x - ((targetContentOffset != NULL) ? targetContentOffset->x : 0),
+    contentOffset.y - ((targetContentOffset != NULL) ? targetContentOffset->y : 0)
   );
 
   if (targetContentOffset != NULL) {
@@ -732,7 +733,7 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
   }
   
   if (_asyncDelegateFlags.asyncDelegateScrollViewWillEndDraggingWithVelocityTargetContentOffset) {
-    [_asyncDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:targetContentOffset];
+    [_asyncDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:(targetContentOffset ? : &contentOffset)];
   }
 }
 
diff --git a/AsyncDisplayKit/ASDisplayNode.mm b/AsyncDisplayKit/ASDisplayNode.mm
index 18e11365dd..a3904603b2 100644
--- a/AsyncDisplayKit/ASDisplayNode.mm
+++ b/AsyncDisplayKit/ASDisplayNode.mm
@@ -2071,7 +2071,8 @@ void recursivelyTriggerDisplayForLayer(CALayer *layer, BOOL shouldBlock)
     return _layoutSpecBlock(self, constrainedSize);
   }
   
-  return nil;
+  ASDisplayNodeAssert(NO, @"-[ASDisplayNode layoutSpecThatFits:] should never fall through to return empty value");
+  return [[ASLayoutSpec alloc] init];
 }
 
 - (ASLayout *)calculatedLayout
diff --git a/AsyncDisplayKit/ASTableView.mm b/AsyncDisplayKit/ASTableView.mm
index 4481ed2d4e..16e5d3cec9 100644
--- a/AsyncDisplayKit/ASTableView.mm
+++ b/AsyncDisplayKit/ASTableView.mm
@@ -704,18 +704,19 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
 
 - (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
 {
+  CGPoint contentOffset = scrollView.contentOffset;
   _deceleratingVelocity = CGPointMake(
-    scrollView.contentOffset.x - ((targetContentOffset != NULL) ? targetContentOffset->x : 0),
-    scrollView.contentOffset.y - ((targetContentOffset != NULL) ? targetContentOffset->y : 0)
+    contentOffset.x - ((targetContentOffset != NULL) ? targetContentOffset->x : 0),
+    contentOffset.y - ((targetContentOffset != NULL) ? targetContentOffset->y : 0)
   );
 
   if (targetContentOffset != NULL) {
     ASDisplayNodeAssert(_batchContext != nil, @"Batch context should exist");
     [self _beginBatchFetchingIfNeededWithScrollView:self forScrollDirection:[self scrollDirection] contentOffset:*targetContentOffset];
   }
-
+  
   if (_asyncDelegateFlags.asyncDelegateScrollViewWillEndDraggingWithVelocityTargetContentOffset) {
-    [_asyncDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:targetContentOffset];
+    [_asyncDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:(targetContentOffset ? : &contentOffset)];
   }
 }
 
diff --git a/AsyncDisplayKit/Details/ASCollectionViewFlowLayoutInspector.h b/AsyncDisplayKit/Details/ASCollectionViewFlowLayoutInspector.h
index 7a9f26e680..423c8302a7 100644
--- a/AsyncDisplayKit/Details/ASCollectionViewFlowLayoutInspector.h
+++ b/AsyncDisplayKit/Details/ASCollectionViewFlowLayoutInspector.h
@@ -48,14 +48,14 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * @discussion A great time to update perform selector caches!
  */
-- (void)didChangeCollectionViewDelegate:(id<ASCollectionDelegate>)delegate;
+- (void)didChangeCollectionViewDelegate:(nullable id<ASCollectionDelegate>)delegate;
 
 /**
  * Allow the inspector to respond to dataSource changes.
  *
  * @discussion A great time to update perform selector caches!
  */
-- (void)didChangeCollectionViewDataSource:(id<ASCollectionDataSource>)dataSource;
+- (void)didChangeCollectionViewDataSource:(nullable id<ASCollectionDataSource>)dataSource;
 
 @end
 
diff --git a/AsyncDisplayKit/Details/ASImageProtocols.h b/AsyncDisplayKit/Details/ASImageProtocols.h
index 676ef4196c..e9074e723b 100644
--- a/AsyncDisplayKit/Details/ASImageProtocols.h
+++ b/AsyncDisplayKit/Details/ASImageProtocols.h
@@ -17,8 +17,8 @@ NS_ASSUME_NONNULL_BEGIN
 
 @protocol ASImageContainerProtocol <NSObject>
 
-- (UIImage *)asdk_image;
-- (NSData *)asdk_animatedImageData;
+- (nullable UIImage *)asdk_image;
+- (nullable NSData *)asdk_animatedImageData;
 
 @end