diff --git a/README.md b/README.md
index 452433e..326e114 100644
--- a/README.md
+++ b/README.md
@@ -49,20 +49,20 @@ If you want to use the custom option, please change the SlideMenuOption class.
 ```swift
 class SlideMenuOption {
     
-    let leftViewWidth: CGFloat = 270.0
-    let leftBezelWidth: CGFloat = 16.0
-    let contentViewScale: CGFloat = 0.96
-    let contentViewOpacity: CGFloat = 0.5
-    let shadowOpacity: CGFloat = 0.0
-    let shadowRadius: CGFloat = 0.0
-    let shadowOffset: CGSize = CGSizeMake(0,0)
-    let panFromBezel: Bool = true
-    let animationDuration: CGFloat = 0.4
-    let rightViewWidth: CGFloat = 270.0
-    let rightBezelWidth: CGFloat = 16.0
-    let rightPanFromBezel: Bool = true
-    let hideStatusBar: Bool = true
-    let pointOfNoReturnWidth: CGFloat = 44.0
+    var leftViewWidth: CGFloat = 270.0
+    var leftBezelWidth: CGFloat = 16.0
+    var contentViewScale: CGFloat = 0.96
+    var contentViewOpacity: CGFloat = 0.5
+    var shadowOpacity: CGFloat = 0.0
+    var shadowRadius: CGFloat = 0.0
+    var shadowOffset: CGSize = CGSizeMake(0,0)
+    var panFromBezel: Bool = true
+    var animationDuration: CGFloat = 0.4
+    var rightViewWidth: CGFloat = 270.0
+    var rightBezelWidth: CGFloat = 16.0
+    var rightPanFromBezel: Bool = true
+    var hideStatusBar: Bool = true
+    var pointOfNoReturnWidth: CGFloat = 44.0
 
     
     init() {