diff --git a/src/include/gpxe/in.h b/src/include/gpxe/in.h
index 89530a559..40e4d4073 100644
--- a/src/include/gpxe/in.h
+++ b/src/include/gpxe/in.h
@@ -62,6 +62,15 @@ struct sockaddr_in {
 	uint16_t sin_port;
 	/** IPv4 address */
 	struct in_addr sin_addr;
+	/** Padding
+	 *
+	 * This ensures that a struct @c sockaddr_tcpip is large
+	 * enough to hold a socket address for any TCP/IP address
+	 * family.
+	 */
+	char pad[ sizeof ( struct sockaddr ) - sizeof ( sa_family_t )
+					     - sizeof ( uint16_t )
+					     - sizeof ( struct in_addr ) ];
 };
 
 /**
diff --git a/src/net/udp.c b/src/net/udp.c
index 89a5b8682..8df76a445 100644
--- a/src/net/udp.c
+++ b/src/net/udp.c
@@ -29,10 +29,10 @@ struct udp_connection {
 	/** Data transfer interface */
 	struct xfer_interface xfer;
 
+	/** Local socket address */
+	struct sockaddr_tcpip local;
 	/** Remote socket address */
 	struct sockaddr_tcpip peer;
-	/** Local port on which the connection receives packets */
-	unsigned int local_port;
 };
 
 /**
@@ -48,22 +48,22 @@ struct tcpip_protocol udp_protocol;
  * Bind UDP connection to local port
  *
  * @v udp		UDP connection
- * @v port		Local port, in network byte order, or zero
  * @ret rc		Return status code
  *
- * Opens the UDP connection and binds to a local port.  If no local
- * port is specified, the first available port will be used.
+ * Opens the UDP connection and binds to the specified local port.  If
+ * no local port is specified, the first available port will be used.
  */
-static int udp_bind ( struct udp_connection *udp, unsigned int port ) {
+static int udp_bind ( struct udp_connection *udp ) {
 	struct udp_connection *existing;
 	static uint16_t try_port = 1024;
 
 	/* If no port specified, find the first available port */
-	if ( ! port ) {
+	if ( ! udp->local.st_port ) {
 		for ( ; try_port ; try_port++ ) {
 			if ( try_port < 1024 )
 				continue;
-			if ( udp_bind ( udp, htons ( try_port ) ) == 0 )
+			udp->local.st_port = htons ( try_port );
+			if ( udp_bind ( udp ) == 0 )
 				return 0;
 		}
 		return -EADDRINUSE;
@@ -71,16 +71,16 @@ static int udp_bind ( struct udp_connection *udp, unsigned int port ) {
 
 	/* Attempt bind to local port */
 	list_for_each_entry ( existing, &udp_conns, list ) {
-		if ( existing->local_port == port ) {
+		if ( existing->local.st_port == udp->local.st_port ) {
 			DBGC ( udp, "UDP %p could not bind: port %d in use\n",
-			       udp, ntohs ( port ) );
+			       udp, ntohs ( udp->local.st_port ) );
 			return -EADDRINUSE;
 		}
 	}
-	udp->local_port = port;
 
 	/* Add to UDP connection list */
-	DBGC ( udp, "UDP %p bound to port %d\n", udp, ntohs ( port ) );
+	DBGC ( udp, "UDP %p bound to port %d\n",
+	       udp, ntohs ( udp->local.st_port ) );
 
 	return 0;
 }
@@ -100,7 +100,6 @@ static int udp_open_common ( struct xfer_interface *xfer,
 	struct sockaddr_tcpip *st_peer = ( struct sockaddr_tcpip * ) peer;
 	struct sockaddr_tcpip *st_local = ( struct sockaddr_tcpip * ) local;
 	struct udp_connection *udp;
-	unsigned int bind_port;
 	int rc;
 
 	/* Allocate and initialise structure */
@@ -111,11 +110,12 @@ static int udp_open_common ( struct xfer_interface *xfer,
 	xfer_init ( &udp->xfer, &udp_xfer_operations, &udp->refcnt );
 	if ( st_peer )
 		memcpy ( &udp->peer, st_peer, sizeof ( udp->peer ) );
+	if ( st_local )
+		memcpy ( &udp->local, st_local, sizeof ( udp->local ) );
 
 	/* Bind to local port */
 	if ( ! promisc ) {
-		bind_port = ( st_local ? st_local->st_port : 0 );
-		if ( ( rc = udp_bind ( udp, bind_port ) ) != 0 )
+		if ( ( rc = udp_bind ( udp ) ) != 0 )
 			goto err;
 	}
 
@@ -201,7 +201,7 @@ static int udp_tx ( struct udp_connection *udp, struct io_buffer *iobuf,
 
 	/* Fill in default values if not explicitly provided */
 	if ( ! src_port )
-		src_port = udp->local_port;
+		src_port = udp->local.st_port;
 	if ( ! dest )
 		dest = &udp->peer;
 
@@ -231,17 +231,24 @@ static int udp_tx ( struct udp_connection *udp, struct io_buffer *iobuf,
 }
 
 /**
- * Identify UDP connection by local port number
+ * Identify UDP connection by local address
  *
- * @v local_port	Local port (in network-endian order)
+ * @v local		Local address
  * @ret udp		UDP connection, or NULL
  */
-static struct udp_connection * udp_demux ( unsigned int local_port ) {
+static struct udp_connection * udp_demux ( struct sockaddr_tcpip *local ) {
+	static const struct sockaddr_tcpip empty_sockaddr;
 	struct udp_connection *udp;
 
 	list_for_each_entry ( udp, &udp_conns, list ) {
-		if ( ( udp->local_port == local_port ) ||
-		     ( udp->local_port == 0 ) ) {
+		if ( ( ( udp->local.st_family == local->st_family ) ||
+		       ( udp->local.st_family == 0 ) ) &&
+		     ( ( udp->local.st_port == local->st_port ) ||
+		       ( udp->local.st_port == 0 ) ) &&
+		     ( ( memcmp ( udp->local.pad, local->pad,
+				  sizeof ( udp->local.pad ) ) == 0 ) ||
+		       ( memcmp ( udp->local.pad, empty_sockaddr.pad,
+				  sizeof ( udp->local.pad ) ) == 0 ) ) ) {
 			return udp;
 		}
 	}
@@ -300,7 +307,7 @@ static int udp_rx ( struct io_buffer *iobuf, struct sockaddr_tcpip *st_src,
 	/* Parse parameters from header and strip header */
 	st_src->st_port = udphdr->src;
 	st_dest->st_port = udphdr->dest;
-	udp = udp_demux ( udphdr->dest );
+	udp = udp_demux ( st_dest );
 	iob_unput ( iobuf, ( iob_len ( iobuf ) - ulen ) );
 	iob_pull ( iobuf, sizeof ( *udphdr ) );