diff --git a/CHANGELOG.md b/CHANGELOG.md
index cb50329d..cb0dbbd0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,8 +1,8 @@
 ArduinoJson: change log
 =======================
 
-HEAD
-----
+v5.1.0
+------
 
 * Added support of `long long` (issue #171)
 * Moved all build settings to `ArduinoJson/Configuration.hpp`
diff --git a/library.json b/library.json
index e3b2bc5a..869368ba 100644
--- a/library.json
+++ b/library.json
@@ -6,7 +6,7 @@
     "type": "git",
     "url": "https://github.com/bblanchon/ArduinoJson.git"
   },
-  "version": "5.0.8",
+  "version": "5.1.0-beta.1",
   "authors": {
     "name": "Benoit Blanchon",
     "url": "http://blog.benoitblanchon.fr"
diff --git a/library.properties b/library.properties
index 64ec0e0a..dd313313 100644
--- a/library.properties
+++ b/library.properties
@@ -1,5 +1,5 @@
 name=ArduinoJson
-version=5.0.8
+version=5.1.0-beta.1
 author=Benoit Blanchon <blog.benoitblanchon.fr>
 maintainer=Benoit Blanchon <blog.benoitblanchon.fr>
 sentence=An efficient and elegant JSON library for Arduino.