diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 572f4e7bd3ff..6e49ec6f3adc 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -817,10 +817,6 @@ static const __u32 acm_tty_speed[] = {
 	2500000, 3000000, 3500000, 4000000
 };
 
-static const __u8 acm_tty_size[] = {
-	5, 6, 7, 8
-};
-
 static void acm_tty_set_termios(struct tty_struct *tty,
 						struct ktermios *termios_old)
 {
@@ -834,7 +830,21 @@ static void acm_tty_set_termios(struct tty_struct *tty,
 	newline.bParityType = termios->c_cflag & PARENB ?
 				(termios->c_cflag & PARODD ? 1 : 2) +
 				(termios->c_cflag & CMSPAR ? 2 : 0) : 0;
-	newline.bDataBits = acm_tty_size[(termios->c_cflag & CSIZE) >> 4];
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		newline.bDataBits = 5;
+		break;
+	case CS6:
+		newline.bDataBits = 6;
+		break;
+	case CS7:
+		newline.bDataBits = 7;
+		break;
+	case CS8:
+	default:
+		newline.bDataBits = 8;
+		break;
+	}
 	/* FIXME: Needs to clear unsupported bits in the termios */
 	acm->clocal = ((termios->c_cflag & CLOCAL) != 0);