diff --git a/firmware/src/app.rs b/firmware/src/app.rs
index 5641898..8e9abfa 100644
--- a/firmware/src/app.rs
+++ b/firmware/src/app.rs
@@ -215,8 +215,8 @@ impl App {
                             {
                                 warn!(
                                     "App: SysEx does not start with magic number; first {} bytes = {}. dropping.",
-                                    MAGIC_NUMBER,
-                                    sysex[..MAGIC_NUMBER_LEN]
+                                    MAGIC_NUMBER_LEN.min(sysex.len()),
+                                    sysex[..MAGIC_NUMBER_LEN.min(sysex.len())]
                                 );
                                 continue;
                             }