diff --git a/qla2x00t-32gbit/qla_def.h b/qla2x00t-32gbit/qla_def.h
index 8dc76a5f9..804b4af98 100644
--- a/qla2x00t-32gbit/qla_def.h
+++ b/qla2x00t-32gbit/qla_def.h
@@ -1008,6 +1008,11 @@ struct mbx_cmd_32 {
 #define MBS_LINK_DOWN_ERROR		0x400B
 #define MBS_DIAG_ECHO_TEST_ERROR	0x400C
 
+static inline bool qla2xxx_is_valid_mbs(unsigned int mbs)
+{
+	return MBS_COMMAND_COMPLETE <= mbs && mbs <= MBS_DIAG_ECHO_TEST_ERROR;
+}
+
 /*
  * ISP mailbox asynchronous event status codes
  */
diff --git a/qla2x00t-32gbit/qla_init.c b/qla2x00t-32gbit/qla_init.c
index 04bd42f7e..0afdd8f56 100644
--- a/qla2x00t-32gbit/qla_init.c
+++ b/qla2x00t-32gbit/qla_init.c
@@ -478,6 +478,9 @@ void qla24xx_handle_adisc_event(scsi_qla_host_t *vha, struct event_arg *ea)
 	    fcport->fw_login_state, ea->rc, fcport->login_gen, ea->sp->gen2,
 	    fcport->rscn_gen, ea->sp->gen1, fcport->loop_id);
 
+	WARN_ONCE(!qla2xxx_is_valid_mbs(ea->data[0]), "mbs: %#x\n",
+		  ea->data[0]);
+
 	if (ea->data[0] != MBS_COMMAND_COMPLETE) {
 		ql_dbg(ql_dbg_disc, vha, 0x2066,
 		    "%s %s: adisc fail: post delete\n",
@@ -1894,6 +1897,9 @@ qla24xx_async_abort_command(srb_t *sp)
 static void
 qla24xx_handle_prli_done_event(struct scsi_qla_host *vha, struct event_arg *ea)
 {
+	WARN_ONCE(!qla2xxx_is_valid_mbs(ea->data[0]), "mbs: %#x\n",
+		  ea->data[0]);
+
 	switch (ea->data[0]) {
 	case MBS_COMMAND_COMPLETE:
 		ql_dbg(ql_dbg_disc, vha, 0x2118, "%s %d %s post gpdb\n",
@@ -1978,6 +1984,9 @@ qla24xx_handle_plogi_done_event(struct scsi_qla_host *vha, struct event_arg *ea)
 		return;
 	}
 
+	WARN_ONCE(!qla2xxx_is_valid_mbs(ea->data[0]), "mbs: %#x\n",
+		  ea->data[0]);
+
 	switch (ea->data[0]) {
 	case MBS_COMMAND_COMPLETE:
 		/*