diff --git a/src/fs/bundle.ts b/src/fs/bundle.ts
index 6c886f3..a03a76d 100644
--- a/src/fs/bundle.ts
+++ b/src/fs/bundle.ts
@@ -42,7 +42,7 @@ export class Bundle {
 
   async addResource(absoluteFileName: string, content?: Buffer | string) {
     let length = 0
-    if (content) {
+    if (content !== undefined) {
       length = Buffer.byteLength(content)
     } else {
       const stats = await stat(absoluteFileName)