diff --git a/boot/zephyr/serial_adapter.c b/boot/zephyr/serial_adapter.c
index 63dca02..896ed52 100644
--- a/boot/zephyr/serial_adapter.c
+++ b/boot/zephyr/serial_adapter.c
@@ -47,7 +47,7 @@
 static sys_slist_t avail_queue;
 static sys_slist_t lines_queue;
 
-static u16_t cur;
+static uint16_t cur;
 
 static int boot_uart_fifo_getline(char **line);
 static int boot_uart_fifo_init(void);
@@ -118,7 +118,7 @@
 boot_uart_fifo_callback(struct device *dev)
 {
 	static struct line_input *cmd;
-	u8_t byte;
+	uint8_t byte;
 	int rx;
 
 	uart_irq_update(uart_dev);
@@ -203,7 +203,7 @@
 		}
 	}
 #endif
-	u8_t c;
+	uint8_t c;
 
 	if (!uart_dev) {
 		return (-1);