diff --git a/boot/zephyr/boards/nrf51_pca10028.conf b/boot/zephyr/boards/nrf51_pca10028.conf
index 61b6568..bd4eaac 100644
--- a/boot/zephyr/boards/nrf51_pca10028.conf
+++ b/boot/zephyr/boards/nrf51_pca10028.conf
@@ -1,5 +1,6 @@
-# Due the small boot partition can't use logging and debug optimalization
-# out-off-the-box. For using these features need to increase boot partition via
-# zephyr DTS.
-CONFIG_BOOT_HAVE_LOGGING=n
+# Due the small boot partition, we can't enable logging or the debug
+# optimization level out off the box. You need to increase the boot
+# partition size with a zephyr DTS overlay to make MCUboot's debug
+# builds fit.
+CONFIG_LOG=n
 CONFIG_SIZE_OPTIMIZATIONS=y
diff --git a/boot/zephyr/boards/nrf52840_pca10059.conf b/boot/zephyr/boards/nrf52840_pca10059.conf
index fadde6a..8c59700 100644
--- a/boot/zephyr/boards/nrf52840_pca10059.conf
+++ b/boot/zephyr/boards/nrf52840_pca10059.conf
@@ -1,7 +1,7 @@
 # The UART is used for Serial Recovery, so logging requires
 # an RTT console, which is not available out of the box on this board.
 # Disable logging.
-CONFIG_BOOT_HAVE_LOGGING=n
+CONFIG_LOG=n
 
 # Serial
 CONFIG_SERIAL=y