diff --git a/boot/zephyr/Kconfig b/boot/zephyr/Kconfig
index 4db769e..33b5b8c 100644
--- a/boot/zephyr/Kconfig
+++ b/boot/zephyr/Kconfig
@@ -33,6 +33,7 @@
 	select REBOOT
 	select UART_INTERRUPT_DRIVEN
 	select SERIAL
+	select BASE64
 	select NEWLIB_LIBC
 	help
 	  Enable serial recovery feature in mcuboot.