diff --git a/SECURITY.md b/SECURITY.md
index b5138a396a..ca75122b57 100644
--- a/SECURITY.md
+++ b/SECURITY.md
@@ -9,6 +9,7 @@ currently being supported with security updates.
 
 | Version | Supported          |
 | ------- | ------------------ |
+| 5.4.x   | :white_check_mark: |
 | 5.3.x   | :white_check_mark: |
 | 5.2.x   | :white_check_mark: |
 | 5.1.x   | :white_check_mark: |
diff --git a/package-lock.json b/package-lock.json
index f0f5d2a6db..5d7aec7901 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,6 +1,6 @@
 {
 	"name": "WordPress",
-	"version": "5.4.0",
+	"version": "5.5.0",
 	"lockfileVersion": 1,
 	"requires": true,
 	"dependencies": {
diff --git a/package.json b/package.json
index 40e873d043..195aecdd6e 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "WordPress",
-	"version": "5.4.0",
+	"version": "5.5.0",
 	"description": "WordPress is open source software you can use to create a beautiful website, blog, or app.",
 	"repository": {
 		"type": "svn",
diff --git a/src/wp-includes/version.php b/src/wp-includes/version.php
index ecc7a7717a..3cb65cb0cd 100644
--- a/src/wp-includes/version.php
+++ b/src/wp-includes/version.php
@@ -13,7 +13,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '5.4-RC1-47424-src';
+$wp_version = '5.5-alpha-47426-src';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.