diff --git a/Library/Homebrew/os/mac/xcode.rb b/Library/Homebrew/os/mac/xcode.rb
index 20ce6b74fc..885ef57e0f 100644
--- a/Library/Homebrew/os/mac/xcode.rb
+++ b/Library/Homebrew/os/mac/xcode.rb
@@ -216,6 +216,7 @@ module OS
         # on the older supported platform for that Xcode release, i.e there's no
         # CLT package for 10.11 that contains the Clang version from Xcode 8.
         case MacOS.version
+        when "10.13" then "900.0.22.8"
         when "10.12" then "802.0.42"
         when "10.11" then "800.0.42.1"
         when "10.10" then "700.1.81"