diff --git a/Library/Homebrew/os/mac/xcode.rb b/Library/Homebrew/os/mac/xcode.rb
index dd87318a35..8799de22ae 100644
--- a/Library/Homebrew/os/mac/xcode.rb
+++ b/Library/Homebrew/os/mac/xcode.rb
@@ -211,7 +211,7 @@ module OS
       end
 
       def separate_header_package?
-        MacOS.version >= :mojave
+        version >= "10"
       end
 
       def headers_installed?