diff --git a/sim/src/main.rs b/sim/src/main.rs
index 27474c8..e33a39d 100644
--- a/sim/src/main.rs
+++ b/sim/src/main.rs
@@ -229,7 +229,8 @@
 
     assert_eq!(c::boot_go(&mut fl, &areadesc), 0);
     // Write boot_ok
-    fl.write(0x040000 - align, &[1]).unwrap();
+    let ok = [1u8, 0, 0, 0, 0, 0, 0, 0];
+    fl.write(0x040000 - align, &ok[..align]).unwrap();
     assert_eq!(c::boot_go(&mut fl, &areadesc), 0);
     fl
 }