diff --git a/Library/Homebrew/os/mac/version.rb b/Library/Homebrew/os/mac/version.rb
index 802ec30352..89016bb4d1 100644
--- a/Library/Homebrew/os/mac/version.rb
+++ b/Library/Homebrew/os/mac/version.rb
@@ -4,6 +4,7 @@ module OS
   module Mac
     class Version < ::Version
       SYMBOLS = {
+        high_sierra: "10.13",
         sierra: "10.12",
         el_capitan: "10.11",
         yosemite: "10.10",