diff --git a/lib/index.js b/lib/index.js
index e7e64a7..84e6e27 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -22,6 +22,8 @@ function createPreprocessor(options, preconfig, basePath, emitter, logger) {
                 return bundle.generate(config);
             })
             .then(({ code, map }) => {
+                file.sourceMap = map;
+
                 const sourcemap =
                     (config.output && config.output.sourcemap) ||
                     config.sourcemap;