diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 498e606..b4d11eb 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -11,11 +11,11 @@ jobs:
     continue-on-error: ${{ matrix.rust == 'nightly' }}
     strategy:
       matrix:
-        # Test on stable, MSRV 1.36, and nightly.
+        # Test on stable, MSRV 1.40, and nightly.
         # Failure is permitted on nightly.
         rust:
           - stable
-          - 1.36.0
+          - 1.40.0
           - nightly
 
         features:
@@ -57,11 +57,11 @@ jobs:
     continue-on-error: ${{ matrix.rust == 'nightly' }}
     strategy:
       matrix:
-        # Test on stable, MSRV 1.36, and nightly.
+        # Test on stable, MSRV 1.40, and nightly.
         # Failure is permitted on nightly.
         rust:
           - stable
-          - 1.36.0
+          - 1.40.0
           - nightly
 
         features:
diff --git a/README.md b/README.md
index a240a15..edcc963 100644
--- a/README.md
+++ b/README.md
@@ -6,7 +6,7 @@ include complicated compile-time computations, such as macro or type tricks, eve
 at cost of performance degradation.
 
 _smoltcp_ does not need heap allocation *at all*, is [extensively documented][docs],
-and compiles on stable Rust 1.36 and later.
+and compiles on stable Rust 1.40 and later.
 
 _smoltcp_ achieves [~Gbps of throughput](#examplesbenchmarkrs) when tested against
 the Linux TCP stack in loopback mode.
diff --git a/src/iface/ethernet.rs b/src/iface/ethernet.rs
index f6a1267..0a0d13e 100644
--- a/src/iface/ethernet.rs
+++ b/src/iface/ethernet.rs
@@ -678,7 +678,6 @@ impl<'b, 'c, 'e, DeviceT> Interface<'b, 'c, 'e, DeviceT>
                     Socket::Tcp(ref mut socket) =>
                         socket.dispatch(timestamp, &caps, |response|
                             respond!(IpPacket::Tcp(response))),
-                    Socket::__Nonexhaustive(_) => unreachable!()
                 };
 
             match (device_result, socket_result) {
@@ -800,7 +799,8 @@ impl<'b, 'c, 'e> InterfaceInner<'b, 'c, 'e> {
             .filter_map(
                 |addr| match *addr {
                     IpCidr::Ipv4(cidr) => Some(cidr.address()),
-                    _ => None,
+                    #[cfg(feature = "proto-ipv6")]
+                    IpCidr::Ipv6(_) => None
                 })
             .next()
     }
@@ -886,8 +886,6 @@ impl<'b, 'c, 'e> InterfaceInner<'b, 'c, 'e> {
                     Ok(None)
                 }
             }
-
-            _ => Err(Error::Unrecognized)
         }
     }
 
@@ -1253,7 +1251,6 @@ impl<'b, 'c, 'e> InterfaceInner<'b, 'c, 'e> {
                         }
                     }
                 }
-                _ => return Err(Error::Unrecognized),
             }
         }
         self.process_nxt_hdr(sockets, timestamp, ipv6_repr, hbh_repr.next_header,
@@ -1421,8 +1418,7 @@ impl<'b, 'c, 'e> InterfaceInner<'b, 'c, 'e> {
                 };
                 Ok(self.icmpv6_reply(ipv6_repr, icmpv6_reply_repr))
             },
-            IpRepr::Unspecified { .. } |
-            IpRepr::__Nonexhaustive => Err(Error::Unaddressable),
+            IpRepr::Unspecified { .. } => Err(Error::Unaddressable),
         }
     }
 
@@ -1467,7 +1463,6 @@ impl<'b, 'c, 'e> InterfaceInner<'b, 'c, 'e> {
                 let dst_hardware_addr =
                     match arp_repr {
                         ArpRepr::EthernetIpv4 { target_hardware_addr, .. } => target_hardware_addr,
-                        _ => unreachable!()
                     };
 
                 self.dispatch_ethernet(tx_token, timestamp, arp_repr.buffer_len(), |mut frame| {
@@ -1555,8 +1550,6 @@ impl<'b, 'c, 'e> InterfaceInner<'b, 'c, 'e> {
                             b[12], b[13],
                             b[14], b[15],
                         ])),
-                    IpAddress::__Nonexhaustive =>
-                        unreachable!()
                 };
             if let Some(hardware_addr) = hardware_addr {
                 return Ok((hardware_addr, tx_token))
@@ -1770,7 +1763,7 @@ mod test {
     impl phy::TxToken for MockTxToken {
         fn consume<R, F>(self, _: Instant, _: usize, _: F) -> Result<R>
                 where F: FnOnce(&mut [u8]) -> Result<R> {
-            Err(Error::__Nonexhaustive)
+            Err(Error::Unaddressable)
         }
     }
 
diff --git a/src/lib.rs b/src/lib.rs
index 0eb50e4..7d18e89 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -116,6 +116,7 @@ pub mod dhcp;
 
 /// The error type for the networking stack.
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum Error {
     /// An operation cannot proceed because a buffer is empty or full.
     Exhausted,
@@ -148,9 +149,6 @@ pub enum Error {
     /// An incoming packet was recognized but contradicted internal state.
     /// E.g. a TCP packet addressed to a socket that doesn't exist.
     Dropped,
-
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 /// The result type for the networking stack.
@@ -169,7 +167,6 @@ impl fmt::Display for Error {
             Error::Fragmented    => write!(f, "fragmented packet"),
             Error::Malformed     => write!(f, "malformed packet"),
             Error::Dropped       => write!(f, "dropped by socket"),
-            Error::__Nonexhaustive => unreachable!()
         }
     }
 }
diff --git a/src/socket/mod.rs b/src/socket/mod.rs
index c81b2f0..d7a971b 100644
--- a/src/socket/mod.rs
+++ b/src/socket/mod.rs
@@ -11,7 +11,6 @@ The interface implemented by this module uses explicit buffering: you decide on
 size for a buffer, allocate it, and let the networking stack use it.
 */
 
-use core::marker::PhantomData;
 use crate::time::Instant;
 
 mod meta;
@@ -91,8 +90,6 @@ pub enum Socket<'a> {
     Udp(UdpSocket<'a>),
     #[cfg(feature = "socket-tcp")]
     Tcp(TcpSocket<'a>),
-    #[doc(hidden)]
-    __Nonexhaustive(PhantomData<&'a ()>)
 }
 
 macro_rules! dispatch_socket {
@@ -112,7 +109,6 @@ macro_rules! dispatch_socket {
             &$( $mut_ )* Socket::Udp(ref $( $mut_ )* $socket) => $code,
             #[cfg(feature = "socket-tcp")]
             &$( $mut_ )* Socket::Tcp(ref $( $mut_ )* $socket) => $code,
-            &$( $mut_ )* Socket::__Nonexhaustive(_) => unreachable!()
         }
     };
 }
@@ -154,9 +150,10 @@ macro_rules! from_socket {
         impl<'a> AnySocket<'a> for $socket {
             fn downcast<'c>(ref_: SocketRef<'c, Socket<'a>>) ->
                            Option<SocketRef<'c, Self>> {
-                match SocketRef::into_inner(ref_) {
-                    &mut Socket::$variant(ref mut socket) => Some(SocketRef::new(socket)),
-                    _ => None,
+                if let Socket::$variant(ref mut socket) = SocketRef::into_inner(ref_) {
+                    Some(SocketRef::new(socket))
+                } else {
+                    None
                 }
             }
         }
diff --git a/src/socket/raw.rs b/src/socket/raw.rs
index 2b99792..e4e60ed 100644
--- a/src/socket/raw.rs
+++ b/src/socket/raw.rs
@@ -257,7 +257,6 @@ impl<'a> RawSocket<'a> {
                     Ok((IpRepr::Ipv6(ipv6_repr), packet.payload()))
                 }
                 IpVersion::Unspecified => unreachable!(),
-                IpVersion::__Nonexhaustive => unreachable!()
             }
         }
 
diff --git a/src/socket/set.rs b/src/socket/set.rs
index 8f0bc01..883bed8 100644
--- a/src/socket/set.rs
+++ b/src/socket/set.rs
@@ -155,7 +155,6 @@ impl<'a, 'b: 'a> Set<'a, 'b> {
                         } else {
                             socket.close()
                         },
-                    Socket::__Nonexhaustive(_) => unreachable!()
                 }
             }
             if may_remove {
diff --git a/src/wire/arp.rs b/src/wire/arp.rs
index 150adbf..e213b29 100644
--- a/src/wire/arp.rs
+++ b/src/wire/arp.rs
@@ -252,6 +252,7 @@ use crate::wire::{EthernetAddress, Ipv4Address};
 
 /// A high-level representation of an Address Resolution Protocol packet.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
+#[non_exhaustive]
 pub enum Repr {
     /// An Ethernet and IPv4 Address Resolution Protocol packet.
     EthernetIpv4 {
@@ -261,8 +262,6 @@ pub enum Repr {
         target_hardware_addr: EthernetAddress,
         target_protocol_addr: Ipv4Address
     },
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 impl Repr {
@@ -292,7 +291,6 @@ impl Repr {
     pub fn buffer_len(&self) -> usize {
         match *self {
             Repr::EthernetIpv4 { .. } => field::TPA(6, 4).end,
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -314,7 +312,6 @@ impl Repr {
                 packet.set_target_hardware_addr(target_hardware_addr.as_bytes());
                 packet.set_target_protocol_addr(target_protocol_addr.as_bytes());
             },
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 }
@@ -351,7 +348,6 @@ impl fmt::Display for Repr {
                        target_hardware_addr, target_protocol_addr,
                        operation)
             },
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 }
diff --git a/src/wire/icmpv4.rs b/src/wire/icmpv4.rs
index fae318a..5748c89 100644
--- a/src/wire/icmpv4.rs
+++ b/src/wire/icmpv4.rs
@@ -366,6 +366,7 @@ impl<T: AsRef<[u8]>> AsRef<[u8]> for Packet<T> {
 
 /// A high-level representation of an Internet Control Message Protocol version 4 packet header.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
+#[non_exhaustive]
 pub enum Repr<'a> {
     EchoRequest {
         ident:  u16,
@@ -382,8 +383,6 @@ pub enum Repr<'a> {
         header: Ipv4Repr,
         data:   &'a [u8]
     },
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 impl<'a> Repr<'a> {
@@ -446,7 +445,6 @@ impl<'a> Repr<'a> {
             &Repr::DstUnreachable { header, data, .. } => {
                 field::UNUSED.end + header.buffer_len() + data.len()
             }
-            &Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -483,8 +481,6 @@ impl<'a> Repr<'a> {
                 let payload = &mut ip_packet.into_inner()[header.buffer_len()..];
                 payload.copy_from_slice(&data[..])
             }
-
-            Repr::__Nonexhaustive => unreachable!()
         }
 
         if checksum_caps.icmpv4.tx() {
@@ -526,7 +522,6 @@ impl<'a> fmt::Display for Repr<'a> {
             Repr::DstUnreachable { reason, .. } =>
                write!(f, "ICMPv4 destination unreachable ({})",
                       reason),
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 }
diff --git a/src/wire/icmpv6.rs b/src/wire/icmpv6.rs
index b3e49a1..bd23244 100644
--- a/src/wire/icmpv6.rs
+++ b/src/wire/icmpv6.rs
@@ -503,6 +503,7 @@ impl<T: AsRef<[u8]>> AsRef<[u8]> for Packet<T> {
 
 /// A high-level representation of an Internet Control Message Protocol version 6 packet header.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
+#[non_exhaustive]
 pub enum Repr<'a> {
     DstUnreachable {
         reason: DstUnreachable,
@@ -538,8 +539,6 @@ pub enum Repr<'a> {
     #[cfg(feature = "ethernet")]
     Ndisc(NdiscRepr<'a>),
     Mld(MldRepr<'a>),
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 impl<'a> Repr<'a> {
@@ -647,7 +646,6 @@ impl<'a> Repr<'a> {
             &Repr::Mld(mld) => {
                 mld.buffer_len()
             },
-            &Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -720,8 +718,6 @@ impl<'a> Repr<'a> {
             Repr::Mld(mld) => {
                 mld.emit(packet)
             },
-
-            Repr::__Nonexhaustive => unreachable!(),
         }
 
         if checksum_caps.icmpv6.tx() {
diff --git a/src/wire/ip.rs b/src/wire/ip.rs
index 1b6acae..f6f6777 100644
--- a/src/wire/ip.rs
+++ b/src/wire/ip.rs
@@ -10,14 +10,13 @@ use crate::wire::{Ipv6Address, Ipv6Cidr, Ipv6Packet, Ipv6Repr};
 
 /// Internet protocol version.
 #[derive(Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
+#[non_exhaustive]
 pub enum Version {
     Unspecified,
     #[cfg(feature = "proto-ipv4")]
     Ipv4,
     #[cfg(feature = "proto-ipv6")]
     Ipv6,
-    #[doc(hidden)]
-    __Nonexhaustive,
 }
 
 impl Version {
@@ -44,7 +43,6 @@ impl fmt::Display for Version {
             Version::Ipv4 => write!(f, "IPv4"),
             #[cfg(feature = "proto-ipv6")]
             Version::Ipv6 => write!(f, "IPv6"),
-            Version::__Nonexhaustive => unreachable!()
         }
     }
 }
@@ -85,6 +83,7 @@ impl fmt::Display for Protocol {
 
 /// An internetworking address.
 #[derive(Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
+#[non_exhaustive]
 pub enum Address {
     /// An unspecified address.
     /// May be used as a placeholder for storage where the address is not assigned yet.
@@ -95,8 +94,6 @@ pub enum Address {
     /// An IPv6 address.
     #[cfg(feature = "proto-ipv6")]
     Ipv6(Ipv6Address),
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 impl Address {
@@ -122,7 +119,6 @@ impl Address {
             Address::Ipv4(ref addr)      => addr.as_bytes(),
             #[cfg(feature = "proto-ipv6")]
             Address::Ipv6(ref addr)      => addr.as_bytes(),
-            Address::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -134,7 +130,6 @@ impl Address {
             Address::Ipv4(addr)      => addr.is_unicast(),
             #[cfg(feature = "proto-ipv6")]
             Address::Ipv6(addr)      => addr.is_unicast(),
-            Address::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -146,7 +141,6 @@ impl Address {
             Address::Ipv4(addr)      => addr.is_multicast(),
             #[cfg(feature = "proto-ipv6")]
             Address::Ipv6(addr)      => addr.is_multicast(),
-            Address::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -158,7 +152,6 @@ impl Address {
             Address::Ipv4(addr)      => addr.is_broadcast(),
             #[cfg(feature = "proto-ipv6")]
             Address::Ipv6(_)         => false,
-            Address::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -170,7 +163,6 @@ impl Address {
             Address::Ipv4(addr)      => addr.is_unspecified(),
             #[cfg(feature = "proto-ipv6")]
             Address::Ipv6(addr)      => addr.is_unspecified(),
-            Address::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -182,7 +174,6 @@ impl Address {
             Address::Ipv4(_)         => Address::Ipv4(Ipv4Address::UNSPECIFIED),
             #[cfg(feature = "proto-ipv6")]
             Address::Ipv6(_)         => Address::Ipv6(Ipv6Address::UNSPECIFIED),
-            Address::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -265,7 +256,6 @@ impl fmt::Display for Address {
             Address::Ipv4(addr)      => write!(f, "{}", addr),
             #[cfg(feature = "proto-ipv6")]
             Address::Ipv6(addr)      => write!(f, "{}", addr),
-            Address::__Nonexhaustive => unreachable!()
         }
     }
 }
@@ -273,13 +263,12 @@ impl fmt::Display for Address {
 /// A specification of a CIDR block, containing an address and a variable-length
 /// subnet masking prefix length.
 #[derive(Debug, Hash, PartialEq, Eq, PartialOrd, Ord, Clone, Copy)]
+#[non_exhaustive]
 pub enum Cidr {
     #[cfg(feature = "proto-ipv4")]
     Ipv4(Ipv4Cidr),
     #[cfg(feature = "proto-ipv6")]
     Ipv6(Ipv6Cidr),
-    #[doc(hidden)]
-    __Nonexhaustive,
 }
 
 impl Cidr {
@@ -296,8 +285,6 @@ impl Cidr {
             Address::Ipv6(addr) => Cidr::Ipv6(Ipv6Cidr::new(addr, prefix_len)),
             Address::Unspecified =>
                 panic!("a CIDR block cannot be based on an unspecified address"),
-            Address::__Nonexhaustive =>
-                unreachable!()
         }
     }
 
@@ -308,7 +295,6 @@ impl Cidr {
             Cidr::Ipv4(cidr)      => Address::Ipv4(cidr.address()),
             #[cfg(feature = "proto-ipv6")]
             Cidr::Ipv6(cidr)      => Address::Ipv6(cidr.address()),
-            Cidr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -319,7 +305,6 @@ impl Cidr {
             Cidr::Ipv4(cidr)      => cidr.prefix_len(),
             #[cfg(feature = "proto-ipv6")]
             Cidr::Ipv6(cidr)      => cidr.prefix_len(),
-            Cidr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -340,9 +325,6 @@ impl Cidr {
                 // a fully unspecified address covers both IPv4 and IPv6,
                 // and no CIDR block can do that.
                 false,
-            (&Cidr::__Nonexhaustive, _) |
-            (_, &Address::__Nonexhaustive) =>
-                unreachable!()
         }
     }
 
@@ -359,9 +341,6 @@ impl Cidr {
             #[cfg(all(feature = "proto-ipv6", feature = "proto-ipv4"))]
             (&Cidr::Ipv4(_), &Cidr::Ipv6(_)) | (&Cidr::Ipv6(_), &Cidr::Ipv4(_)) =>
                 false,
-            (&Cidr::__Nonexhaustive, _) |
-            (_, &Cidr::__Nonexhaustive) =>
-                unreachable!()
         }
     }
 }
@@ -387,7 +366,6 @@ impl fmt::Display for Cidr {
             Cidr::Ipv4(cidr)      => write!(f, "{}", cidr),
             #[cfg(feature = "proto-ipv6")]
             Cidr::Ipv6(cidr)      => write!(f, "{}", cidr),
-            Cidr::__Nonexhaustive => unreachable!()
         }
     }
 }
@@ -470,6 +448,7 @@ impl<T: Into<Address>> From<(T, u16)> for Endpoint {
 /// high-level representation for some IP protocol version, or an unspecified representation,
 /// which permits the `IpAddress::Unspecified` addresses.
 #[derive(Debug, Clone, PartialEq, Eq)]
+#[non_exhaustive]
 pub enum Repr {
     Unspecified {
         src_addr:    Address,
@@ -482,8 +461,6 @@ pub enum Repr {
     Ipv4(Ipv4Repr),
     #[cfg(feature = "proto-ipv6")]
     Ipv6(Ipv6Repr),
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 #[cfg(feature = "proto-ipv4")]
@@ -509,7 +486,6 @@ impl Repr {
             Repr::Ipv4(_) => Version::Ipv4,
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(_) => Version::Ipv6,
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -521,7 +497,6 @@ impl Repr {
             Repr::Ipv4(repr) => Address::Ipv4(repr.src_addr),
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(repr) => Address::Ipv6(repr.src_addr),
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -533,7 +508,6 @@ impl Repr {
             Repr::Ipv4(repr) => Address::Ipv4(repr.dst_addr),
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(repr) => Address::Ipv6(repr.dst_addr),
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -545,7 +519,6 @@ impl Repr {
             Repr::Ipv4(repr) => repr.protocol,
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(repr) => repr.next_header,
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -557,7 +530,6 @@ impl Repr {
             Repr::Ipv4(repr) => repr.payload_len,
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(repr) => repr.payload_len,
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -572,7 +544,6 @@ impl Repr {
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(Ipv6Repr { ref mut payload_len, .. }) =>
                 *payload_len = length,
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -584,7 +555,6 @@ impl Repr {
             Repr::Ipv4(Ipv4Repr { hop_limit, .. }) => hop_limit,
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(Ipv6Repr { hop_limit, ..})  => hop_limit,
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -711,8 +681,6 @@ impl Repr {
 
             &Repr::Unspecified { .. } =>
                 panic!("source and destination IP address families do not match"),
-
-            &Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -730,8 +698,6 @@ impl Repr {
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(repr) =>
                 repr.buffer_len(),
-            Repr::__Nonexhaustive =>
-                unreachable!()
         }
     }
 
@@ -749,8 +715,6 @@ impl Repr {
             #[cfg(feature = "proto-ipv6")]
             Repr::Ipv6(repr) =>
                 repr.emit(&mut Ipv6Packet::new_unchecked(buffer)),
-            Repr::__Nonexhaustive =>
-                unreachable!()
         }
     }
 
diff --git a/src/wire/ipv6option.rs b/src/wire/ipv6option.rs
index 18e5dce..7264284 100644
--- a/src/wire/ipv6option.rs
+++ b/src/wire/ipv6option.rs
@@ -214,6 +214,7 @@ impl<'a, T: AsRef<[u8]> + ?Sized> fmt::Display for Ipv6Option<&'a T> {
 
 /// A high-level representation of an IPv6 Extension Header Option.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
+#[non_exhaustive]
 pub enum Repr<'a> {
     Pad1,
     PadN(u8),
@@ -222,9 +223,6 @@ pub enum Repr<'a> {
         length: u8,
         data:   &'a [u8]
     },
-
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 impl<'a> Repr<'a> {
@@ -253,8 +251,6 @@ impl<'a> Repr<'a> {
                field::DATA(length).end,
             Repr::Unknown{ length, .. } =>
                field::DATA(length).end,
-
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -276,8 +272,6 @@ impl<'a> Repr<'a> {
                 opt.set_data_len(length);
                 opt.data_mut().copy_from_slice(&data[..length as usize]);
             }
-
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 }
@@ -352,8 +346,6 @@ impl<'a> fmt::Display for Repr<'a> {
                write!(f, "{} length={} ", Type::PadN, len),
             Repr::Unknown{ type_, length, .. } =>
                write!(f, "{} length={} ", type_, length),
-
-            Repr::__Nonexhaustive => unreachable!()
         }
     }
 }
diff --git a/src/wire/ipv6routing.rs b/src/wire/ipv6routing.rs
index 93a2775..f407899 100644
--- a/src/wire/ipv6routing.rs
+++ b/src/wire/ipv6routing.rs
@@ -389,6 +389,7 @@ impl<'a, T: AsRef<[u8]> + ?Sized> fmt::Display for Header<&'a T> {
 
 /// A high-level representation of an IPv6 Routing Header.
 #[derive(Debug, PartialEq, Eq, Clone, Copy)]
+#[non_exhaustive]
 pub enum Repr<'a> {
     Type2 {
         /// The type of header immediately following the Routing header.
@@ -417,9 +418,6 @@ pub enum Repr<'a> {
         /// Vector of addresses, numbered 1 to `n`.
         addresses:      &'a[u8],
     },
-
-    #[doc(hidden)]
-    __Nonexhaustive
 }
 
 
@@ -458,8 +456,6 @@ impl<'a> Repr<'a> {
             &Repr::Rpl { length, .. } | &Repr::Type2 { length, .. } => {
                 field::DATA(length).end
             }
-
-            &Repr::__Nonexhaustive => unreachable!()
         }
     }
 
@@ -485,8 +481,6 @@ impl<'a> Repr<'a> {
                 header.clear_reserved();
                 header.set_addresses(addresses);
             }
-
-            Repr::__Nonexhaustive => unreachable!(),
         }
     }
 }
@@ -502,8 +496,6 @@ impl<'a> fmt::Display for Repr<'a> {
                 write!(f, "IPv6 Routing next_hdr={} length={} type={} seg_left={} cmpr_i={} cmpr_e={} pad={}",
                        next_header, length, Type::Rpl, segments_left, cmpr_i, cmpr_e, pad)
             }
-
-            Repr::__Nonexhaustive => unreachable!(),
         }
     }
 }