diff --git a/Tools/px_romfs_pruner.py b/Tools/px_romfs_pruner.py
index aef1cc7a3b..78e4e69f72 100644
--- a/Tools/px_romfs_pruner.py
+++ b/Tools/px_romfs_pruner.py
@@ -76,7 +76,7 @@ def main():
                                                         pruned_content += line
 
                         # overwrite old scratch file
-                        with open(file_path, "w") as f:
+                        with open(file_path, "wb") as f:
                                 f.write(pruned_content)