diff --git a/rust/kernel/io/register.rs b/rust/kernel/io/register.rs
index f924c7c7c1db..66449377a0b7 100644
--- a/rust/kernel/io/register.rs
+++ b/rust/kernel/io/register.rs
@@ -448,7 +448,7 @@ fn into_io_op(self) -> (FixedRegisterLoc<T>, T) {
 ///
 /// register! {
 ///     FIXED_REG(u32) @ 0x100 {
-///         16:8 high_byte;
+///         15:8 high_byte;
 ///         7:0  low_byte;
 ///     }
 /// }