diff --git a/mavlink-core/src/lib.rs b/mavlink-core/src/lib.rs
index eac97934b70b2b1b610f7914eed9efa2134fd9e4..3be0db377a1f8b997c0a6ee875f0c08ec13045ad 100644
--- a/mavlink-core/src/lib.rs
+++ b/mavlink-core/src/lib.rs
@@ -511,7 +511,7 @@ impl MAVLinkV2MessageRaw {
     }
 
     #[inline]
-    pub fn header(&mut self) -> &[u8] {
+    pub fn header(&self) -> &[u8] {
         &self.0[1..=Self::HEADER_SIZE]
     }