diff --git a/package.json b/package.json
index e8c9842c4b72..754ed41a54b6 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "private": true,
-  "version": "16.4.1",
+  "version": "16.4.3-alpha.0",
   "workspaces": [
     "packages/*"
   ],
diff --git a/packages/create-subscription/package.json b/packages/create-subscription/package.json
index ccfcb5dfe822..6fc16864137f 100644
--- a/packages/create-subscription/package.json
+++ b/packages/create-subscription/package.json
@@ -1,7 +1,7 @@
 {
   "name": "create-subscription",
   "description": "utility for subscribing to external data sources inside React components",
-  "version": "16.4.1",
+  "version": "16.4.3-alpha.0",
   "repository": "facebook/react",
   "files": [
     "LICENSE",
diff --git a/packages/react-art/package.json b/packages/react-art/package.json
index 7a41213e1ce2..a33b1e482337 100644
--- a/packages/react-art/package.json
+++ b/packages/react-art/package.json
@@ -1,7 +1,7 @@
 {
   "name": "react-art",
   "description": "React ART is a JavaScript library for drawing vector graphics using React. It provides declarative and reactive bindings to the ART library. Using the same declarative API you can render the output to either Canvas, SVG or VML (IE8).",
-  "version": "16.4.1",
+  "version": "16.4.3-alpha.0",
   "main": "index.js",
   "repository": "facebook/react",
   "keywords": [
diff --git a/packages/react-dom/package.json b/packages/react-dom/package.json
index 8fbb203d048a..9f89e24c767d 100644
--- a/packages/react-dom/package.json
+++ b/packages/react-dom/package.json
@@ -1,6 +1,6 @@
 {
   "name": "react-dom",
-  "version": "16.4.1",
+  "version": "16.4.3-alpha.0",
   "description": "React package for working with the DOM.",
   "main": "index.js",
   "repository": "facebook/react",
diff --git a/packages/react-is/package.json b/packages/react-is/package.json
index 9b41e5e81b08..09728faafe1a 100644
--- a/packages/react-is/package.json
+++ b/packages/react-is/package.json
@@ -1,6 +1,6 @@
 {
   "name": "react-is",
-  "version": "16.4.1",
+  "version": "16.4.3-alpha.0",
   "description": "Brand checking of React Elements.",
   "main": "index.js",
   "repository": "facebook/react",
diff --git a/packages/react-test-renderer/package.json b/packages/react-test-renderer/package.json
index ff09dffa9a97..5ff1da8bf394 100644
--- a/packages/react-test-renderer/package.json
+++ b/packages/react-test-renderer/package.json
@@ -1,6 +1,6 @@
 {
   "name": "react-test-renderer",
-  "version": "16.4.1",
+  "version": "16.4.3-alpha.0",
   "description": "React package for snapshot testing.",
   "main": "index.js",
   "repository": "facebook/react",
@@ -17,7 +17,7 @@
   "dependencies": {
     "object-assign": "^4.1.1",
     "prop-types": "^15.6.2",
-    "react-is": "^16.4.1"
+    "react-is": "^16.4.3-alpha.0"
   },
   "peerDependencies": {
     "react": "^16.0.0"
diff --git a/packages/react/package.json b/packages/react/package.json
index 7be32deba4f7..6c9ad1ad537f 100644
--- a/packages/react/package.json
+++ b/packages/react/package.json
@@ -4,7 +4,7 @@
   "keywords": [
     "react"
   ],
-  "version": "16.4.1",
+  "version": "16.4.3-alpha.0",
   "homepage": "https://reactjs.org/",
   "bugs": "https://github.com/facebook/react/issues",
   "license": "MIT",
diff --git a/packages/shared/ReactVersion.js b/packages/shared/ReactVersion.js
index 47ea28d34921..865a46fe3fe3 100644
--- a/packages/shared/ReactVersion.js
+++ b/packages/shared/ReactVersion.js
@@ -8,4 +8,4 @@
 'use strict';
 
 // TODO: this is special because it gets imported during build.
-module.exports = '16.4.1';
+module.exports = '16.4.3-alpha.0';