diff --git a/quinn-proto/src/connection/mod.rs b/quinn-proto/src/connection/mod.rs
index b0e4cabd2..970cce0df 100644
--- a/quinn-proto/src/connection/mod.rs
+++ b/quinn-proto/src/connection/mod.rs
@@ -365,6 +365,7 @@ where
                     contents: buf,
                     ecn: None,
                     segment_size: None,
+                    src_ip: self.local_ip,
                 });
             }
         }
@@ -554,6 +555,7 @@ where
                 None
             },
             segment_size: None,
+            src_ip: self.local_ip,
         })
     }
 
diff --git a/quinn-proto/src/endpoint.rs b/quinn-proto/src/endpoint.rs
index 151724818..72cb25a79 100644
--- a/quinn-proto/src/endpoint.rs
+++ b/quinn-proto/src/endpoint.rs
@@ -190,6 +190,7 @@ where
                         ecn: None,
                         contents: buf,
                         segment_size: None,
+                        src_ip: local_ip,
                     });
                     return None;
                 }
@@ -253,7 +254,7 @@ where
 
         if !self.is_server() {
             debug!("packet for unrecognized connection {}", dst_cid);
-            self.stateless_reset(datagram_len, remote, &dst_cid);
+            self.stateless_reset(datagram_len, remote, local_ip, &dst_cid);
             return None;
         }
 
@@ -288,7 +289,7 @@ where
         //
 
         if !dst_cid.is_empty() {
-            self.stateless_reset(datagram_len, remote, &dst_cid);
+            self.stateless_reset(datagram_len, remote, local_ip, &dst_cid);
         } else {
             trace!("dropping unrecognized short packet without ID");
         }
@@ -299,6 +300,7 @@ where
         &mut self,
         inciting_dgram_len: usize,
         remote: SocketAddr,
+        local_ip: Option<IpAddr>,
         dst_cid: &ConnectionId,
     ) {
         /// Minimum amount of padding for the stateless reset to look like a short-header packet
@@ -336,6 +338,7 @@ where
             ecn: None,
             contents: buf,
             segment_size: None,
+            src_ip: local_ip,
         });
     }
 
@@ -535,6 +538,7 @@ where
             debug!("refusing connection");
             self.initial_close(
                 remote,
+                local_ip,
                 crypto,
                 &src_cid,
                 &temp_loc_cid,
@@ -553,6 +557,7 @@ where
             );
             self.initial_close(
                 remote,
+                local_ip,
                 crypto,
                 &src_cid,
                 &temp_loc_cid,
@@ -590,6 +595,7 @@ where
                     ecn: None,
                     contents: buf,
                     segment_size: None,
+                    src_ip: local_ip,
                 });
                 return None;
             }
@@ -608,6 +614,7 @@ where
                     debug!("rejecting invalid stateless retry token");
                     self.initial_close(
                         remote,
+                        local_ip,
                         crypto,
                         &src_cid,
                         &temp_loc_cid,
@@ -645,7 +652,7 @@ where
                 debug!("handshake failed: {}", e);
                 self.handle_event(ch, EndpointEvent(EndpointEventInner::Drained));
                 if let ConnectionError::TransportError(e) = e {
-                    self.initial_close(remote, crypto, &src_cid, &temp_loc_cid, e);
+                    self.initial_close(remote, local_ip, crypto, &src_cid, &temp_loc_cid, e);
                 }
                 None
             }
@@ -655,6 +662,7 @@ where
     fn initial_close(
         &mut self,
         destination: SocketAddr,
+        local_ip: Option<IpAddr>,
         crypto: &Keys<S>,
         remote_id: &ConnectionId,
         local_id: &ConnectionId,
@@ -683,6 +691,7 @@ where
             ecn: None,
             contents: buf,
             segment_size: None,
+            src_ip: local_ip,
         })
     }
 
diff --git a/quinn-proto/src/lib.rs b/quinn-proto/src/lib.rs
index 6703e9441..23d210f72 100644
--- a/quinn-proto/src/lib.rs
+++ b/quinn-proto/src/lib.rs
@@ -18,7 +18,13 @@
 #![allow(clippy::cognitive_complexity)]
 #![allow(clippy::too_many_arguments)]
 
-use std::{convert::TryInto, fmt, net::SocketAddr, ops, time::Duration};
+use std::{
+    convert::TryInto,
+    fmt,
+    net::{IpAddr, SocketAddr},
+    ops,
+    time::Duration,
+};
 
 mod cid_queue;
 #[doc(hidden)]
@@ -277,6 +283,8 @@ pub struct Transmit {
     /// The segment size if this transmission contains multiple datagrams.
     /// This is `None` if the transmit only contains a single datagram
     pub segment_size: Option<usize>,
+    /// Optional source IP address for the datagram
+    pub src_ip: Option<IpAddr>,
 }
 
 //
diff --git a/quinn/src/platform/unix.rs b/quinn/src/platform/unix.rs
index f99ad4100..36b7a8788 100644
--- a/quinn/src/platform/unix.rs
+++ b/quinn/src/platform/unix.rs
@@ -2,7 +2,7 @@ use std::{
     io,
     io::IoSliceMut,
     mem::{self, MaybeUninit},
-    net::{IpAddr, SocketAddr, SocketAddrV4, SocketAddrV6},
+    net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6},
     os::unix::io::AsRawFd,
     ptr,
 };
@@ -273,7 +273,7 @@ pub fn caps() -> UdpCapabilities {
     *CAPABILITIES
 }
 
-const CMSG_LEN: usize = 64;
+const CMSG_LEN: usize = 80;
 
 fn prepare_msg(
     transmit: &Transmit,
@@ -312,6 +312,32 @@ fn prepare_msg(
         gso::set_segment_size(&mut encoder, segment_size as u16);
     }
 
+    if let Some(ip) = &transmit.src_ip {
+        if cfg!(target_os = "linux") {
+            match ip {
+                IpAddr::V4(v4) => {
+                    let pktinfo = libc::in_pktinfo {
+                        ipi_ifindex: 0,
+                        ipi_spec_dst: unsafe {
+                            *(v4 as *const Ipv4Addr as *const () as *const libc::in_addr)
+                        },
+                        ipi_addr: libc::in_addr { s_addr: 0 },
+                    };
+                    encoder.push(libc::IPPROTO_IP, libc::IP_PKTINFO, pktinfo);
+                }
+                IpAddr::V6(v6) => {
+                    let pktinfo = libc::in6_pktinfo {
+                        ipi6_ifindex: 0,
+                        ipi6_addr: unsafe {
+                            *(v6 as *const Ipv6Addr as *const () as *const libc::in6_addr)
+                        },
+                    };
+                    encoder.push(libc::IPPROTO_IPV6, libc::IPV6_PKTINFO, pktinfo);
+                }
+            }
+        }
+    }
+
     encoder.finish();
 }