diff --git a/Library/Homebrew/os/mac.rb b/Library/Homebrew/os/mac.rb
index 6dd281ce74..2f47aa2a32 100644
--- a/Library/Homebrew/os/mac.rb
+++ b/Library/Homebrew/os/mac.rb
@@ -212,6 +212,7 @@ module OS
       "6.1.1" => { :clang => "6.0", :clang_build => 600 },
       "6.2"   => { :clang => "6.0", :clang_build => 600 },
       "6.3"   => { :clang => "6.1", :clang_build => 602 },
+      "6.3.1" => { :clang => "6.1", :clang_build => 602 },
     }
 
     def compilers_standard?