diff --git a/Sources/SheetController/SheetContainerViewController.swift b/Sources/SheetController/SheetContainerViewController.swift
index 84077c5..b771ea5 100644
--- a/Sources/SheetController/SheetContainerViewController.swift
+++ b/Sources/SheetController/SheetContainerViewController.swift
@@ -8,7 +8,7 @@
 
 import UIKit
 
-public protocol SheetContainerViewControllerDelegate {
+public protocol SheetContainerViewControllerDelegate: class {
     func sheetContainer(_ sheetContainer: SheetContainerViewController, willSnapToDetent detent: Detent) -> Bool
     func sheetContainer(_ sheetContainer: SheetContainerViewController, didSnapToDetent detent: Detent)
     func sheetContainerContentScrollView(_ sheetContainer: SheetContainerViewController) -> UIScrollView?
@@ -29,9 +29,9 @@ public extension SheetContainerViewControllerDelegate {
     }
 }
 
-public class SheetContainerViewController: UIViewController {
+open class SheetContainerViewController: UIViewController {
 
-    public var delegate: SheetContainerViewControllerDelegate?
+    public weak var delegate: SheetContainerViewControllerDelegate?
     
     public let content: UIViewController
     
@@ -72,7 +72,7 @@ public class SheetContainerViewController: UIViewController {
         fatalError("init(coder:) has not been implemented")
     }
 
-    override public func viewDidLoad() {
+    override open func viewDidLoad() {
         super.viewDidLoad()
         
         dimmingView = UIView()