diff --git a/index.js b/index.js
index bfa7d4f..11800c9 100644
--- a/index.js
+++ b/index.js
@@ -82,7 +82,8 @@ function createStream (opts) {
     let ast
     const string = transformAst(source, {
       locations: true,
-      ecmaVersion: 9
+      ecmaVersion: 9,
+      inputFilename: file
     }, (node) => {
       if (node.type === 'Program') ast = node
     })