diff --git a/boot/zephyr/boards/nrf52840dongle_nrf52840.conf b/boot/zephyr/boards/nrf52840dongle_nrf52840.conf
index c1a93844..d219f351 100644
--- a/boot/zephyr/boards/nrf52840dongle_nrf52840.conf
+++ b/boot/zephyr/boards/nrf52840dongle_nrf52840.conf
@@ -3,13 +3,10 @@
 # Disable logging.
 CONFIG_LOG=n
 
-# The build won't fit on the partition allocated for it without size
-# optimizations.
-CONFIG_SIZE_OPTIMIZATIONS=y
-
 # Serial
+CONFIG_CONSOLE=n
 CONFIG_SERIAL=y
-CONFIG_UART_NRFX=y
+CONFIG_UART_NRFX=n
 CONFIG_UART_INTERRUPT_DRIVEN=y
 CONFIG_UART_LINE_CTRL=y
 
@@ -25,7 +22,5 @@ CONFIG_MULTITHREADING=y
 CONFIG_USB_DEVICE_STACK=y
 CONFIG_USB_DEVICE_REMOTE_WAKEUP=n
 CONFIG_USB_DEVICE_PRODUCT="MCUBOOT"
-CONFIG_USB_COMPOSITE_DEVICE=n
-CONFIG_USB_MASS_STORAGE=n
 
 CONFIG_NORDIC_QSPI_NOR=n
diff --git a/boot/zephyr/usb_cdc_acm_log_recovery.conf b/boot/zephyr/usb_cdc_acm_log_recovery.conf
index ae412fed..2312c0ec 100644
--- a/boot/zephyr/usb_cdc_acm_log_recovery.conf
+++ b/boot/zephyr/usb_cdc_acm_log_recovery.conf
@@ -1,16 +1,11 @@
 CONFIG_LOG=y
 
-# The build won't fit on the partition allocated for it without size
-# optimizations.
-CONFIG_SIZE_OPTIMIZATIONS=y
-
 # Serial
+CONFIG_UART_CONSOLE=n
+CONFIG_CONSOLE=n
 CONFIG_SERIAL=y
 CONFIG_UART_LINE_CTRL=y
 
 # MCUBoot serial
 CONFIG_MCUBOOT_SERIAL=y
 CONFIG_BOOT_SERIAL_CDC_ACM=y
-
-CONFIG_LOG_BACKEND_UART=y
-CONFIG_LOG_BACKEND_RTT=n