gistfile1.diff

diff --git a/kernel/common/global.rb b/kernel/common/global.rb
index fb80419..4cbbd1e 100644
--- a/kernel/common/global.rb
+++ b/kernel/common/global.rb
@@ -84,7 +84,7 @@ module Rubinius
     end
 
     def illegal_set(*args)
-      raise RuntimeError, "unable to set global"
+      raise NameError, "#{args[0]} is a read-only variable"
     end
 
     def set_hook(var, getter=nil, setter=nil, &block)