diff --git a/README.md b/README.md
index 3c546bc..d7ddffb 100644
--- a/README.md
+++ b/README.md
@@ -54,7 +54,7 @@
 macOS, Ubuntu Linux LTS, and the latest Ubuntu Linux release are the current
 supported host development operating systems.
 
-For macOS, you need [Xcode 9.0 beta 2](https://developer.apple.com/xcode/downloads/).
+For macOS, you need [Xcode 9.0 beta 4](https://developer.apple.com/xcode/downloads/).
 
 For Ubuntu, you'll need the following development dependencies: