diff --git a/crates/engine/src/tests.rs b/crates/engine/src/tests.rs
index 8d6562d5d..3bf54d12f 100644
--- a/crates/engine/src/tests.rs
+++ b/crates/engine/src/tests.rs
@@ -3612,6 +3612,7 @@ fn xls_fixture() -> Vec<u8> {
     let mut put = |at: usize, v: &[u8]| b[at..at + v.len()].copy_from_slice(v);
     put(0, &[0xD0, 0xCF, 0x11, 0xE0, 0xA1, 0xB1, 0x1A, 0xE1]);
     put(26, &3u16.to_le_bytes());
+    put(28, &0xFFFEu16.to_le_bytes()); // byte order ([MS-CFB] 2.2)
     put(30, &9u16.to_le_bytes());
     put(32, &6u16.to_le_bytes());
     put(44, &1u32.to_le_bytes());