diff --git a/Library/Homebrew/os/mac/xquartz.rb b/Library/Homebrew/os/mac/xquartz.rb
index fd676b0772..6ac970b188 100644
--- a/Library/Homebrew/os/mac/xquartz.rb
+++ b/Library/Homebrew/os/mac/xquartz.rb
@@ -70,6 +70,7 @@ module OS
       # educated guess as to what version is installed.
       def guess_system_version
         case MacOS.version
+        when "10.4" then "1.1.3"
         when "10.5" then "2.1.6"
         when "10.6" then "2.3.6"
         when "10.7" then "2.6.3"