diff --git a/scst/src/dev_handlers/scst_vdisk.c b/scst/src/dev_handlers/scst_vdisk.c
index 3e301810f..0a92f4871 100644
--- a/scst/src/dev_handlers/scst_vdisk.c
+++ b/scst/src/dev_handlers/scst_vdisk.c
@@ -1082,6 +1082,11 @@ static enum compl_status_e vdisk_exec_send_diagnostic(struct vdisk_cmd_params *p
 	return CMD_SUCCEEDED;
 }
 
+static enum compl_status_e vdisk_exec_format_unit(struct vdisk_cmd_params *p)
+{
+	return CMD_SUCCEEDED;
+}
+
 static enum compl_status_e vdisk_invalid_opcode(struct vdisk_cmd_params *p)
 {
 	TRACE_DBG("Invalid opcode %d", p->cmd->cdb[0]);
@@ -1112,7 +1117,8 @@ static enum compl_status_e vdisk_invalid_opcode(struct vdisk_cmd_params *p)
 	[WRITE_SAME] = vdisk_exec_write_same,				\
 	[WRITE_SAME_16] = vdisk_exec_write_same,			\
 	[MAINTENANCE_IN] = vdisk_exec_maintenance_in,			\
-	[SEND_DIAGNOSTIC] = vdisk_exec_send_diagnostic,
+	[SEND_DIAGNOSTIC] = vdisk_exec_send_diagnostic,			\
+	[FORMAT_UNIT] = vdisk_exec_format_unit,
 
 static vdisk_op_fn blockio_ops[256] = {
 	[READ_6] = blockio_exec_read,
diff --git a/scst/src/scst_lib.c b/scst/src/scst_lib.c
index 3b178c65e..f8964e382 100644
--- a/scst/src/scst_lib.c
+++ b/scst/src/scst_lib.c
@@ -6380,6 +6380,9 @@ static int get_cdb_info_fmt(struct scst_cmd *cmd,
 	cmd->op_flags |= SCST_LBA_NOT_VALID;
 	cmd->lba = 0;
 
+	/* It is not really supported anyway */
+	cmd->data_len = 0;
+
 	if (cmd->cdb[1] & 0x10/*FMTDATA*/) {
 		cmd->data_direction = SCST_DATA_WRITE;
 		cmd->op_flags |= SCST_UNKNOWN_LENGTH;