diff --git a/README.md b/README.md
index 04822a82..8fa376e1 100644
--- a/README.md
+++ b/README.md
@@ -95,7 +95,7 @@ dayView.updateStyle(style)
 ## Requirements
 
 - iOS 9.0+
-- Swift 5.1+
+- Swift 4+ (Library is written in Swift 5)
 
 ## Dependencies
 - **[Neon](https://github.com/mamaral/Neon)** is used for declarative layout