diff --git a/astlpc.c b/astlpc.c
index 0e7e9f8..455276d 100644
--- a/astlpc.c
+++ b/astlpc.c
@@ -821,9 +821,10 @@
 		       __func__, len, hdr->src, hdr->dest, hdr->flags_seq_tag);
 
 	if (len > astlpc->proto->body_size(astlpc->layout.tx.size)) {
-		astlpc_prwarn(astlpc, "invalid TX len %" PRIu32 ": %" PRIu32, len,
-				astlpc->proto->body_size(astlpc->layout.tx.size));
-		return -1;
+		astlpc_prwarn(astlpc, "invalid TX len %" PRIu32 ": %" PRIu32,
+			      len,
+			      astlpc->proto->body_size(astlpc->layout.tx.size));
+		return -EMSGSIZE;
 	}
 
 	mctp_binding_set_tx_enabled(b, false);
diff --git a/core.c b/core.c
index e878175..2f87692 100644
--- a/core.c
+++ b/core.c
@@ -694,13 +694,26 @@
 		int rc;
 
 		rc = mctp_packet_tx(bus, pkt);
-		if (rc)
+		switch (rc) {
+		/* If transmission succeded, or */
+		case 0:
+		/* If the packet is somehow too large */
+		case -EMSGSIZE:
+			/* Drop the packet */
+			bus->tx_queue_head = pkt->next;
+			mctp_pktbuf_free(pkt);
 			break;
 
-		bus->tx_queue_head = pkt->next;
-		mctp_pktbuf_free(pkt);
+		/* If the binding was busy, or */
+		case -EBUSY:
+		/* Some other unknown error occurred */
+		default:
+			/* Make sure the tail pointer is consistent and retry later */
+			goto cleanup_tail;
+		};
 	}
 
+cleanup_tail:
 	if (!bus->tx_queue_head)
 		bus->tx_queue_tail = NULL;
 
diff --git a/libmctp.h b/libmctp.h
index 497d536..8e13c29 100644
--- a/libmctp.h
+++ b/libmctp.h
@@ -107,6 +107,14 @@
 		    uint8_t msg_tag, void *msg, size_t msg_len);
 
 /* hardware bindings */
+
+/**
+ * @tx: Binding function to transmit one packet on the interface
+ *      Return:
+ *      * 0 - Success, pktbuf can be released
+ *	* -EMSGSIZE - Packet exceeds binding MTU, pktbuf must be dropped
+ *	* -EBUSY - Packet unable to be transmitted, pktbuf must be retained
+ */
 struct mctp_binding {
 	const char *name;
 	uint8_t version;
diff --git a/serial.c b/serial.c
index 5e37507..35c4a02 100644
--- a/serial.c
+++ b/serial.c
@@ -154,7 +154,7 @@
 
 	len = mctp_serial_pkt_escape(pkt, NULL);
 	if (len + sizeof(*hdr) + sizeof(*tlr) > sizeof(serial->txbuf))
-		return -1;
+		return -EMSGSIZE;
 
 	mctp_serial_pkt_escape(pkt, buf);