diff --git a/ChangeLog.md b/ChangeLog.md
index e6b86315c1c7ae23d9527fe1e33683de57937604..d14aaddf7e8c84a9d63a79bb021eeb287d942478 100644
--- a/ChangeLog.md
+++ b/ChangeLog.md
@@ -2,6 +2,12 @@
 
 All notable changes are documented in this file using the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
 
+## [3.0.6] - 2023-03-02
+
+### Changed
+
+* Do not use implicitly nullable parameters
+
 ## [3.0.5] - 2023-03-01
 
 * No code changes, only updated `.gitattributes` to not export non-essential files.
@@ -63,6 +69,7 @@ All notable changes are documented in this file using the [Keep a CHANGELOG](htt
 
 * This component is no longer supported on PHP 5.6
 
+[3.0.6]: https://github.com/sebastianbergmann/diff/compare/3.0.5...3.0.6
 [3.0.5]: https://github.com/sebastianbergmann/diff/compare/3.0.4...3.0.5
 [3.0.4]: https://github.com/sebastianbergmann/diff/compare/3.0.3...3.0.4
 [3.0.3]: https://github.com/sebastianbergmann/diff/compare/3.0.2...3.0.3
diff --git a/src/Differ.php b/src/Differ.php
index 3c90a5a13dd5d5a9b437584d3571dff81d2759c3..74e314493619d91941d090baf628db1e63f2b20a 100644
--- a/src/Differ.php
+++ b/src/Differ.php
@@ -64,7 +64,7 @@ final class Differ
      *
      * @return string
      */
-    public function diff($from, $to, LongestCommonSubsequenceCalculator $lcs = null): string
+    public function diff($from, $to, ?LongestCommonSubsequenceCalculator $lcs = null): string
     {
         $diff = $this->diffToArray(
             $this->normalizeDiffInput($from),
@@ -92,7 +92,7 @@ final class Differ
      *
      * @return array
      */
-    public function diffToArray($from, $to, LongestCommonSubsequenceCalculator $lcs = null): array
+    public function diffToArray($from, $to, ?LongestCommonSubsequenceCalculator $lcs = null): array
     {
         if (\is_string($from)) {
             $from = $this->splitStringByLines($from);
diff --git a/src/Exception/ConfigurationException.php b/src/Exception/ConfigurationException.php
index 78f16fde4436dd3f1257565a84d206389d4e53af..f57ec9502c034f9e21d0e9969dec3f8937f4251d 100644
--- a/src/Exception/ConfigurationException.php
+++ b/src/Exception/ConfigurationException.php
@@ -24,7 +24,7 @@ final class ConfigurationException extends InvalidArgumentException
         string $expected,
         $value,
         int $code = 0,
-        \Exception $previous = null
+        ?\Exception $previous = null
     ) {
         parent::__construct(
             \sprintf(