diff --git a/script/release/uploaders/upload-index-json.py b/script/release/uploaders/upload-index-json.py
index a96ffbc556a5c..e90eed678c028 100755
--- a/script/release/uploaders/upload-index-json.py
+++ b/script/release/uploaders/upload-index-json.py
@@ -56,7 +56,7 @@ def main():
 
     new_content = get_content()
 
-    with open(index_json, "w") as f:
+    with open(index_json, "wb") as f:
       f.write(new_content)
 
     store_artifact(OUT_DIR, 'atom-shell/dist', [index_json])