diff --git a/lib/sourcemaps.js b/lib/sourcemaps.js
index 2807928..c5848a7 100644
--- a/lib/sourcemaps.js
+++ b/lib/sourcemaps.js
@@ -72,7 +72,7 @@ function generateSourceMap(fileHref, sources, files) {
 
 function addSourceMappingURLToSource(file, source) {
   const sourcemapFlag = '//# sourceMappingURL=';
-  let ref = `\n${sourcemapFlag}${file.vname}\n`;
+  let ref = `\n${sourcemapFlag}/${file.vname}\n`;
   if (source.ext === 'html') {
     ref = `<script>${ref}<\/script>`;
     const marker = /<\/(body|html)>/;