diff --git a/src/iterators/drain.rs b/src/iterators/drain.rs
index 07f5e546..7fef4aaa 100644
--- a/src/iterators/drain.rs
+++ b/src/iterators/drain.rs
@@ -1,3 +1,9 @@
+#[cfg(feature = "defmt")]
+use defmt::{
+    Format as DeFormat,
+    Formatter as DeFormatter,
+    write as dewrite
+};
 use {
     super::super::{
         SmallVec,
@@ -246,3 +252,12 @@ impl<Item: Debug, const INLINE: usize, Heap: Allocator> Debug for Drain<'_, Item
         f.debug_tuple("Drain").field(&self.iter.as_slice()).finish()
     }
 }
+
+#[cfg(feature = "defmt")]
+impl<Item: DeFormat, const INLINE: usize, Heap: Allocator> DeFormat
+    for Drain<'_, Item, INLINE, Heap>
+{
+    fn format(&self, fmt: DeFormatter) {
+        dewrite!(fmt, "Drain({=[?]})", self.iter.as_slice());
+    }
+}
diff --git a/src/iterators/extractif.rs b/src/iterators/extractif.rs
index e0ee1b5f..38066b51 100644
--- a/src/iterators/extractif.rs
+++ b/src/iterators/extractif.rs
@@ -1,3 +1,9 @@
+#[cfg(feature = "defmt")]
+use defmt::{
+    Format as DeFormat,
+    Formatter as DeFormatter,
+    write as dewrite
+};
 use {
     super::super::{
         SmallVec,
@@ -51,6 +57,18 @@ where
     }
 }
 
+#[cfg(feature = "defmt")]
+impl<Item, const INLINE: usize, Heap: Allocator, F> DeFormat
+    for ExtractIf<'_, Item, INLINE, F, Heap>
+where
+    F: FnMut(&mut Item) -> bool,
+    Item: DeFormat
+{
+    fn format(&self, fmt: DeFormatter) {
+        dewrite!(fmt, "ExtractIf({=[?]})", self.vec.as_ref());
+    }
+}
+
 impl<Item, F, const INLINE: usize, Heap: Allocator> Iterator
     for ExtractIf<'_, Item, INLINE, F, Heap>
 where F: FnMut(&mut Item) -> bool
diff --git a/src/iterators/intoiter.rs b/src/iterators/intoiter.rs
index ec08ec90..b02baa91 100644
--- a/src/iterators/intoiter.rs
+++ b/src/iterators/intoiter.rs
@@ -1,3 +1,9 @@
+#[cfg(feature = "defmt")]
+use defmt::{
+    Format as DeFormat,
+    Formatter as DeFormatter,
+    write as dewrite
+};
 use {
     super::super::{
         DropDealloc,
@@ -223,3 +229,12 @@ impl<Item: Debug, const INLINE: usize, Heap: Allocator> Debug for IntoIter<Item,
         f.debug_tuple("IntoIter").field(&self.as_ref()).finish()
     }
 }
+
+#[cfg(feature = "defmt")]
+impl<Item: DeFormat, const INLINE: usize, Heap: Allocator> DeFormat
+    for IntoIter<Item, INLINE, Heap>
+{
+    fn format(&self, fmt: DeFormatter) {
+        dewrite!(fmt, "IntoIter({=[?]})", self.as_ref());
+    }
+}
diff --git a/src/iterators/splice.rs b/src/iterators/splice.rs
index a08086dd..5d0605e6 100644
--- a/src/iterators/splice.rs
+++ b/src/iterators/splice.rs
@@ -1,3 +1,9 @@
+#[cfg(feature = "defmt")]
+use defmt::{
+    Format as DeFormat,
+    Formatter as DeFormatter,
+    write as dewrite
+};
 use {
     super::{
         super::{
@@ -43,6 +49,17 @@ where
     }
 }
 
+#[cfg(feature = "defmt")]
+impl<'valid, I, const INLINE: usize, Heap: Allocator> DeFormat for Splice<'valid, I, INLINE, Heap>
+where
+    I: Iterator + 'valid,
+    <I as Iterator>::Item: DeFormat
+{
+    fn format(&self, fmt: DeFormatter) {
+        dewrite!(fmt, "Splice({})", self.drain);
+    }
+}
+
 impl<I: Iterator, const INLINE: usize, Heap: Allocator> Iterator for Splice<'_, I, INLINE, Heap> {
     type Item = I::Item;
 
diff --git a/src/locatedlength.rs b/src/locatedlength.rs
index fc833347..29022294 100644
--- a/src/locatedlength.rs
+++ b/src/locatedlength.rs
@@ -1,4 +1,17 @@
-use core::marker::PhantomData;
+use core::{
+    fmt::{
+        Debug,
+        Formatter,
+        Result as Format
+    },
+    marker::PhantomData
+};
+#[cfg(feature = "defmt")]
+use defmt::{
+    Format as DeFormat,
+    Formatter as DeFormatter,
+    write as dewrite
+};
 
 /// Vec guarantees that its length is always less than [`isize::MAX`] in
 /// *bytes*.
@@ -23,6 +36,29 @@ impl<Item> Clone for LocatedLength<Item> {
 
 impl<Item> Copy for LocatedLength<Item> {}
 
+impl<Item> Debug for LocatedLength<Item> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Format {
+        let (length, on_heap) = self.parts();
+        f.debug_struct("LocatedLength")
+            .field("length", &length)
+            .field("on_heap", &on_heap)
+            .finish()
+    }
+}
+
+#[cfg(feature = "defmt")]
+impl<Item> DeFormat for LocatedLength<Item> {
+    fn format(&self, fmt: DeFormatter) {
+        let (length, on_heap) = self.parts();
+        dewrite!(
+            fmt,
+            "LocatedLength {{ length: {=usize}, on_heap: {=bool} }}",
+            length,
+            on_heap
+        );
+    }
+}
+
 #[allow(clippy::len_without_is_empty)]
 impl<Item> LocatedLength<Item> {
     const MAX_LEN: usize = usize::MAX >> Self::SHIFT;
diff --git a/src/rawsmallvec.rs b/src/rawsmallvec.rs
index 7c8d8f8e..9b0d39b6 100644
--- a/src/rawsmallvec.rs
+++ b/src/rawsmallvec.rs
@@ -1,3 +1,9 @@
+#[cfg(feature = "defmt")]
+use defmt::{
+    Format as DeFormat,
+    Formatter as DeFormatter,
+    write as dewrite
+};
 use {
     super::{
         allocator::Allocator,
@@ -6,6 +12,11 @@ use {
     },
     core::{
         alloc::Layout,
+        fmt::{
+            Debug,
+            Formatter,
+            Result as Format
+        },
         mem::{
             ManuallyDrop,
             MaybeUninit
@@ -23,6 +34,21 @@ pub union RawSmallVec<Item, const INLINE: usize> {
     pub heap: (NonNull<Item>, usize)
 }
 
+// The active member is tracked by `LocatedLength`, not by the union itself, so
+// neither member can be read safely here.
+impl<Item, const INLINE: usize> Debug for RawSmallVec<Item, INLINE> {
+    fn fmt(&self, f: &mut Formatter<'_>) -> Format {
+        f.debug_struct("RawSmallVec").finish_non_exhaustive()
+    }
+}
+
+#[cfg(feature = "defmt")]
+impl<Item, const INLINE: usize> DeFormat for RawSmallVec<Item, INLINE> {
+    fn format(&self, fmt: DeFormatter) {
+        dewrite!(fmt, "RawSmallVec {{ .. }}");
+    }
+}
+
 impl<Item, const INLINE: usize> RawSmallVec<Item, INLINE> {
     pub const INLINE_CAP: usize = if Self::IS_ZST { usize::MAX } else { INLINE };
     const IS_ZST: bool = size_of::<Item>() == 0;