diff --git a/README.md b/README.md
index e401e6c08d..6be7026506 100644
--- a/README.md
+++ b/README.md
@@ -18,7 +18,7 @@
 [travis]: https://travis-ci.org/mcu-tools/mcuboot
 [license]: https://github.com/mcu-tools/mcuboot/blob/main/LICENSE
 
-This is MCUboot version 2.3.0
+This is MCUboot version 2.4.0-dev
 
 MCUboot is a secure bootloader for 32-bits microcontrollers. It defines a
 common infrastructure for the bootloader and the system flash layout on
diff --git a/boot/zephyr/VERSION b/boot/zephyr/VERSION
index d3e370089e..6d5c8062d5 100644
--- a/boot/zephyr/VERSION
+++ b/boot/zephyr/VERSION
@@ -1,5 +1,5 @@
 VERSION_MAJOR = 2
-VERSION_MINOR = 3
+VERSION_MINOR = 4
 PATCHLEVEL = 0
 VERSION_TWEAK = 0
-EXTRAVERSION =
+EXTRAVERSION = dev
diff --git a/docs/release-notes.d/imgtool-public-ed25519.md b/docs/release-notes.d/imgtool-public-ed25519.md
deleted file mode 100644
index 1eadb248cf..0000000000
--- a/docs/release-notes.d/imgtool-public-ed25519.md
+++ /dev/null
@@ -1,3 +0,0 @@
-- imgtool verify when using a public ed25519 key has been fixed
-  to work rather than show an invalid key type not matching the
-  TLV record error.
diff --git a/docs/release-notes.d/zephyr-folder-paths.md b/docs/release-notes.d/zephyr-folder-paths.md
deleted file mode 100644
index ae5250461a..0000000000
--- a/docs/release-notes.d/zephyr-folder-paths.md
+++ /dev/null
@@ -1,10 +0,0 @@
-- Zephyr signature and encryption key file path handling has now
-  been aligned with Zephyr, this means values can be specified in
-  multiple .conf file and the one that last set it will be the set
-  value. This also means that key files will no longer be found
-  relative to the .conf file and will instead be found relative
-  to the build system ``APPLICATION_CONFIG_DIR`` variable, though
-  the key file strings are now configured which allows for using
-  escaped CMake variables to locate the files, for example with
-  ``\${CMAKE_CURRENT_LIST_DIR}`` to specify a file relative to
-  the folder that the file is in.
diff --git a/docs/release-notes.d/zephyr-watchdog.md b/docs/release-notes.d/zephyr-watchdog.md
deleted file mode 100644
index 9982d86d08..0000000000
--- a/docs/release-notes.d/zephyr-watchdog.md
+++ /dev/null
@@ -1,19 +0,0 @@
-- Watchdog support in Zephyr has been reworked and fixed to allow
-  installing a timeout (with a configurable value) before starting
-  it. The default timeout is set to 1 minute and this feature has
-  been enabled by default. 3 Kconfig options have been added which
-  control how the watchdog is used in MCUboot:
-
-    * ``CONFIG_BOOT_WATCHDOG_SETUP_AT_BOOT`` controls setting up
-      the watchdog in MCUboot (if not set up, it can still be set,
-      if the driver supports this non-compliant behaviour).
-    * ``CONFIG_BOOT_WATCHDOG_INSTALL_TIMEOUT_AT_BOOT`` controls if
-      a timeout is installed at bootup or not.
-    * ``CONFIG_BOOT_WATCHDOG_TIMEOUT_MS`` sets the value of the
-      timeout in ms.
-
-- In addition, Zephyr modules can now over-ride the default
-  watchdog functionality by replacing the weakly defined functions
-  ``mcuboot_watchdog_setup`` and/or ``mcuboot_watchdog_feed``,
-  these functions take no arguments.
-