diff --git a/CHANGELOG.md b/CHANGELOG.md
index a5c14de..b6d1433 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](http://keepachangelog.com/) and this project adheres to [Semantic Versioning](http://semver.org/).
 
+## 4.0.1 - 2022-05-06
+
+### Fixed
+- Fixed an issue where `$value` was not allowed to be `null`
+
 ## 4.0.0 - 2022-05-03
 
 ### Changed
diff --git a/composer.json b/composer.json
index 680d085..221988b 100644
--- a/composer.json
+++ b/composer.json
@@ -2,7 +2,7 @@
     "name": "percipiolondon/craft-colour-swatches",
     "description": "Let clients choose from a predefined set of colours and utilise associated colour codes and class names in your templates.",
     "type": "craft-plugin",
-    "version": "4.0.0",
+    "version": "4.0.1",
     "keywords": [
         "craft",
         "cms",
diff --git a/src/models/ColourSwatches.php b/src/models/ColourSwatches.php
index e170188..328522d 100644
--- a/src/models/ColourSwatches.php
+++ b/src/models/ColourSwatches.php
@@ -26,9 +26,9 @@ class ColourSwatches extends Model
     /**
      * ColourSwatches constructor.
      *
-     * @param string $value
+     * @param string|null $value
      */
-    public function __construct(string $value)
+    public function __construct(?string $value)
     {
         if ($this->validateJson($value)) {
             $colorData = Json::decode($value);
@@ -42,10 +42,10 @@ public function __construct(string $value)
     // making sure we have json data, returns boolean(true) if this is the case
 
     /**
-     * @param string $value
+     * @param string|null $value
      * @return bool
      */
-    public function validateJson(string $value): bool
+    public function validateJson(?string $value): bool
     {
         $json = Json::decode($value);
         return $json && $value != $json;