diff --git a/drivers/platform/x86/dell/dell-uart-backlight.c b/drivers/platform/x86/dell/dell-uart-backlight.c
index f51eefa87e26..4f074d48a5fe 100644
--- a/drivers/platform/x86/dell/dell-uart-backlight.c
+++ b/drivers/platform/x86/dell/dell-uart-backlight.c
@@ -39,7 +39,7 @@ static struct file *ftty;
 
 unsigned int (*io_serial_in)(struct uart_port *p, int offset);
 int (*uart_write)(struct tty_struct *tty, const unsigned char *buf, int count);
-int (*uart_chars_in_buffer)(struct tty_struct *tty);
+unsigned int (*uart_chars_in_buffer)(struct tty_struct *tty);
 
 static bool force;
 module_param(force, bool, 0444);