diff --git a/Sources/BaseButtonBarPagerTabStripViewController.swift b/Sources/BaseButtonBarPagerTabStripViewController.swift
index 68684ac4..5350049f 100644
--- a/Sources/BaseButtonBarPagerTabStripViewController.swift
+++ b/Sources/BaseButtonBarPagerTabStripViewController.swift
@@ -24,7 +24,7 @@
 
 import Foundation
 
-open class BaseButtonBarPagerTabStripViewController<ButtonBarCellType: UICollectionViewCell>: PagerTabStripViewController, PagerTabStripDataSource, PagerTabStripIsProgressiveDelegate, UICollectionViewDelegate, UICollectionViewDataSource {
+open class BaseButtonBarPagerTabStripViewController<ButtonBarCellType: UICollectionViewCell>: PagerTabStripViewController, PagerTabStripDataSource, PagerTabStripIsProgressiveDelegate, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
 
     public var settings = ButtonBarPagerTabStripSettings()
     public var buttonBarItemSpec: ButtonBarItemSpec<ButtonBarCellType>!
@@ -195,7 +195,7 @@ open class BaseButtonBarPagerTabStripViewController<ButtonBarCellType: UICollect
 
     // MARK: - UICollectionViewDelegateFlowLayut
 
-    @objc open func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
+    @objc open func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
         guard let cellWidthValue = cachedCellWidths?[indexPath.row] else {
             fatalError("cachedCellWidths for \(indexPath.row) must not be nil")
         }
diff --git a/Sources/ButtonBarPagerTabStripViewController.swift b/Sources/ButtonBarPagerTabStripViewController.swift
index 34d64b0f..8c611d8c 100644
--- a/Sources/ButtonBarPagerTabStripViewController.swift
+++ b/Sources/ButtonBarPagerTabStripViewController.swift
@@ -72,7 +72,7 @@ public struct ButtonBarPagerTabStripSettings {
     public var style = Style()
 }
 
-open class ButtonBarPagerTabStripViewController: PagerTabStripViewController, PagerTabStripDataSource, PagerTabStripIsProgressiveDelegate, UICollectionViewDelegate, UICollectionViewDataSource {
+open class ButtonBarPagerTabStripViewController: PagerTabStripViewController, PagerTabStripDataSource, PagerTabStripIsProgressiveDelegate, UICollectionViewDelegate, UICollectionViewDataSource, UICollectionViewDelegateFlowLayout {
 
     public var settings = ButtonBarPagerTabStripSettings()
 
@@ -277,7 +277,7 @@ open class ButtonBarPagerTabStripViewController: PagerTabStripViewController, Pa
 
     // MARK: - UICollectionViewDelegateFlowLayut
 
-    @objc open func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAtIndexPath indexPath: IndexPath) -> CGSize {
+    @objc open func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
         guard let cellWidthValue = cachedCellWidths?[indexPath.row] else {
             fatalError("cachedCellWidths for \(indexPath.row) must not be nil")
         }