diff --git a/package.json b/package.json
index 79ae7a8a..55c23b92 100644
--- a/package.json
+++ b/package.json
@@ -53,6 +53,7 @@
     "module": "./dist/esm/index.js",
     "types": "./dist/commonjs/index.d.ts",
     "files": [
+        "WritableStream.js",
         "dist",
         "src"
     ],