diff --git a/lib/sass/plugin.rb b/lib/sass/plugin.rb
index 0da00cb5..d5ff135f 100644
--- a/lib/sass/plugin.rb
+++ b/lib/sass/plugin.rb
@@ -119,7 +119,7 @@ module Sass
       end
 
       def forbid_update?(name)
-        name[0] == ?_
+        name.sub(/^.*\//, '')[0] == ?_
       end
 
       def stylesheet_needs_update?(name)