diff --git a/CHANGELOG.md b/CHANGELOG.md
index 789c3f3..cfe438b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 ### Fixed
 * Fixed an issue where USB devices were not enumerating on Windows ([#32](https://github.com/rust-embedded-community/usb-device/issues/82))
+* Add optional support for defmt ([#76](https://github.com/rust-embedded-community/usb-device/pull/76))
 
 ...
 
diff --git a/Cargo.toml b/Cargo.toml
index d582a0f..7cbebf9 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -9,6 +9,9 @@ license = "MIT"
 authors = ["Matti Virkkunen <mvirkkunen@gmail.com>"]
 repository = "https://github.com/mvirkkunen/usb-device"
 
+[dependencies]
+defmt = { version = "0.3", optional = true }
+
 [dev-dependencies]
 rusb = "0.8.0"
 rand = "0.6.1"
diff --git a/src/bus.rs b/src/bus.rs
index a6cd31c..e18f8d6 100644
--- a/src/bus.rs
+++ b/src/bus.rs
@@ -281,6 +281,7 @@ impl<B: UsbBus> UsbBusAllocator<B> {
 
 /// A handle for a USB interface that contains its number.
 #[derive(Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub struct InterfaceNumber(u8);
 
 impl From<InterfaceNumber> for u8 {
@@ -291,6 +292,7 @@ impl From<InterfaceNumber> for u8 {
 
 /// A handle for a USB string descriptor that contains its index.
 #[derive(Copy, Clone, Eq, PartialEq)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub struct StringIndex(u8);
 
 impl StringIndex {
diff --git a/src/control.rs b/src/control.rs
index a6bf245..a822457 100644
--- a/src/control.rs
+++ b/src/control.rs
@@ -4,6 +4,7 @@ use core::mem;
 /// Control request type.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub enum RequestType {
     /// Request is a USB standard request. Usually handled by
     /// [`UsbDevice`](crate::device::UsbDevice).
@@ -18,6 +19,7 @@ pub enum RequestType {
 
 /// Control request recipient.
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub enum Recipient {
     /// Request is intended for the entire device.
     Device = 0,
@@ -35,6 +37,7 @@ pub enum Recipient {
 
 /// A control request read from a SETUP packet.
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub struct Request {
     /// Direction of the request.
     pub direction: UsbDirection,
diff --git a/src/control_pipe.rs b/src/control_pipe.rs
index 32fa6c7..877b910 100644
--- a/src/control_pipe.rs
+++ b/src/control_pipe.rs
@@ -5,6 +5,7 @@ use crate::{Result, UsbDirection, UsbError};
 use core::cmp::min;
 
 #[derive(Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 #[allow(unused)]
 enum ControlState {
     Idle,
diff --git a/src/device.rs b/src/device.rs
index 816e044..dc18511 100644
--- a/src/device.rs
+++ b/src/device.rs
@@ -12,6 +12,7 @@ use crate::{Result, UsbDirection};
 /// In general class traffic is only possible in the `Configured` state.
 #[repr(u8)]
 #[derive(PartialEq, Eq, Copy, Clone, Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub enum UsbDeviceState {
     /// The USB device has just been created or reset.
     Default,
diff --git a/src/endpoint.rs b/src/endpoint.rs
index c4758f4..e207d81 100644
--- a/src/endpoint.rs
+++ b/src/endpoint.rs
@@ -33,6 +33,7 @@ pub type EndpointIn<'a, B> = Endpoint<'a, B, In>;
 /// transfer bmAttributes transfer type bits.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub enum EndpointType {
     /// Control endpoint. Used for device management. Only the host can initiate requests. Usually
     /// used only endpoint 0.
@@ -157,6 +158,7 @@ impl<B: UsbBus> Endpoint<'_, B, Out> {
 
 /// Type-safe endpoint address.
 #[derive(Debug, Clone, Copy, Eq, PartialEq)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub struct EndpointAddress(u8);
 
 impl From<u8> for EndpointAddress {
diff --git a/src/lib.rs b/src/lib.rs
index d7744c9..7679fd3 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -38,6 +38,7 @@
 
 /// A USB stack error.
 #[derive(Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub enum UsbError {
     /// An operation would block because the device is currently busy or there is no data available.
     WouldBlock,
@@ -76,6 +77,7 @@ pub enum UsbError {
 /// request types.
 #[repr(u8)]
 #[derive(Copy, Clone, Eq, PartialEq, Debug)]
+#[cfg_attr(feature = "defmt-impl", derive(defmt::Format))]
 pub enum UsbDirection {
     /// Host to device (OUT)
     Out = 0x00,