diff --git a/embassy-stm32/src/rcc/mod.rs b/embassy-stm32/src/rcc/mod.rs
index 0a52089d..d4bd3d6b 100644
--- a/embassy-stm32/src/rcc/mod.rs
+++ b/embassy-stm32/src/rcc/mod.rs
@@ -24,7 +24,8 @@ use crate::time::Hertz;
 mod _version;
 pub use _version::*;
 
-#[derive(Clone, Copy)]
+#[derive(Clone, Copy, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct Clocks {
     pub sys: Hertz,
 
@@ -72,6 +73,7 @@ static mut CLOCK_FREQS: MaybeUninit<Clocks> = MaybeUninit::uninit();
 ///
 /// Safety: Sets a mutable global.
 pub(crate) unsafe fn set_freqs(freqs: Clocks) {
+    debug!("rcc: {:?}", freqs);
     CLOCK_FREQS.as_mut_ptr().write(freqs);
 }
 
diff --git a/embassy-stm32/src/time.rs b/embassy-stm32/src/time.rs
index 49140bbe..975517a4 100644
--- a/embassy-stm32/src/time.rs
+++ b/embassy-stm32/src/time.rs
@@ -2,6 +2,7 @@
 
 /// Hertz
 #[derive(PartialEq, PartialOrd, Clone, Copy, Debug, Eq)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
 pub struct Hertz(pub u32);
 
 impl Hertz {