diff --git a/index.js b/index.js
index 18a1ea7..5ca9cec 100644
--- a/index.js
+++ b/index.js
@@ -34,7 +34,8 @@ module.exports = function (file, opts) {
             vars: vars,
             varModules: { path: path },
             parserOpts: opts && opts.parserOpts,
-            sourceMap: opts && (opts.sourceMap || opts._flags && opts._flags.debug)
+            sourceMap: opts && (opts.sourceMap || opts._flags && opts._flags.debug),
+            inputFilename: file
         }
     );
     return sm;