diff --git a/Sources/PanSlip/PanSlip+UIView.swift b/Sources/PanSlip/PanSlip+UIView.swift
index eefd9e5..ccaf7be 100644
--- a/Sources/PanSlip/PanSlip+UIView.swift
+++ b/Sources/PanSlip/PanSlip+UIView.swift
@@ -37,7 +37,7 @@ extension PanSlip where Base: UIView {
     
     // MARK: - Public methods
     
-    public func enable(slipDirection: PanSlipDirection, slipCompletion: (() -> Void)?) {
+    public func enable(slipDirection: PanSlipDirection, slipCompletion: (() -> Void)? = nil) {
         self.slipDirection = slipDirection
         self.slipCompletion = slipCompletion
         
diff --git a/Sources/PanSlip/PanSlip+UIViewController.swift b/Sources/PanSlip/PanSlip+UIViewController.swift
index fd50024..f34be1f 100644
--- a/Sources/PanSlip/PanSlip+UIViewController.swift
+++ b/Sources/PanSlip/PanSlip+UIViewController.swift
@@ -37,7 +37,7 @@ extension PanSlip where Base: UIViewController {
     
     // MARK: - Public methods
     
-    public func enable(slipDirection: PanSlipDirection, slipCompletion: (() -> Void)?) {
+    public func enable(slipDirection: PanSlipDirection, slipCompletion: (() -> Void)? = nil) {
         self.slipDirection = slipDirection
         self.slipCompletion = slipCompletion