diff --git a/lib/sassc/embedded.rb b/lib/sassc/embedded.rb
index 8078b65..abaed7e 100644
--- a/lib/sassc/embedded.rb
+++ b/lib/sassc/embedded.rb
@@ -231,7 +231,7 @@ def find_file_url(...)
 
     private_constant :FileImporter
 
-    class FileSystemImporter
+    module FileSystemImporter
       class << self
         def resolve_path(path, from_import)
           ext = File.extname(path)