diff --git a/beginner/apps/src/bin/radio-puzzle-4.rs b/beginner/apps/src/bin/radio-puzzle-4.rs
index 49fa4e0..1166e50 100644
--- a/beginner/apps/src/bin/radio-puzzle-4.rs
+++ b/beginner/apps/src/bin/radio-puzzle-4.rs
@@ -22,7 +22,9 @@ fn main() -> ! {
     buffer.push(b'i').expect("buffer full");
 
     // look into the contents so far
-    defmt::println!("{:?}", buffer);
+    defmt::println!("{}", defmt::Debug2Format(&buffer));
+    //                         ^^^^^^^^^^^^^^^^^^^ this adapter is currently needed to log
+    //                                            `StandardRequest` with `defmt`
 
     // or more readable
     // NOTE utf-8 conversion works as long as you only push bytes in the ASCII range (0..=127)