diff --git a/src/main.rs b/src/main.rs
index 10580a1..87e7c88 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -18,7 +18,11 @@ fn fix_file<P>(path: P) -> Result<()>
 where
     P: AsRef<Path>,
 {
-    let mut f = File::open(&path).with_context(|| "failed to open sound bank file")?;
+    let mut f = File::options()
+        .write(true)
+        .read(true)
+        .open(&path)
+        .with_context(|| "failed to open sound bank file")?;
 
     f.seek(SeekFrom::Start(OFFSET_VERSION_NUMBER))
         .with_context(|| "failed to seek to version number offset")?;