diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7a06711..cb09f66 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,10 @@ All releases must adhere to [SemVer 2](https://semver.org/) naming convention an
 ## PHPMarkup [Unreleased]
 Released: TBA. Notable changes:
 
+## PHPMarkup 4.2.5
+Released: 2021-10-08. Notable changes:
+* Fixed: QA tests.
+
 ## PHPMarkup 4.2.4
 Released: 2021-10-08. Notable changes:
 * Added: InnerXML sanitization.
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 58bb5b2..4e3d377 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -4,7 +4,7 @@ First off, thanks for taking the time to contribute!
 
 For local package development use [Docker](https://www.docker.com/products/docker-desktop):
 
-Build Test container
+**Step 1**) Pull code and build Test container
 ```
 git clone https://github.com/Ouxsoft/phpmarkup.git
 cd phpmarkup
@@ -12,18 +12,17 @@ docker build --target test --tag phpmarkup:latest -f Dockerfile .
 docker run -it --mount type=bind,source="$(pwd)"/,target=/application/ phpmarkup:latest composer install
 ```
 
-Run Automated Unit Tests using local volume
-```
-docker run -it --mount type=bind,source="$(pwd)"/,target=/application/ phpmarkup:latest composer test
-```
+**Step 2**) Make code changes.
 
-Run Automated Benchmark Tests using local volume
+**Step 3**) Run Automated QA using local volume
 ```
-docker run -it --mount type=bind,source="$(pwd)"/,target=/application/ phpmarkup:latest ./vendor/bin/phpbench run tests/src/Benchmark --report=default
+docker run -it --mount type=bind,source="$(pwd)"/,target=/application/ phpmarkup:latest composer qa
 ```
 
-Rebuild Docs
+**Step 4**) Rebuild Docs
 ```
 docker build --target docs --tag phpmarkup:docs-latest -f Dockerfile .
 docker run -it --mount type=bind,source="$(pwd)"/,target=/app/ phpmarkup:docs-latest bash -c "cd /app/docs && doxygen Doxyfile && doxyphp2sphinx Ouxsoft::PHPMarkup"
 ```
+
+**Step 5**) Submit PR
\ No newline at end of file
diff --git a/src/Engine.php b/src/Engine.php
index ab40c6c..061ef13 100644
--- a/src/Engine.php
+++ b/src/Engine.php
@@ -395,7 +395,7 @@ public function sanitizeXml(string $xml): string
         // strip args
         $xml = preg_replace("/<arg.*?>(.*)?<\/arg>/im", '', $xml);
         // strip INDEX_ATTRIBUTE
-        $xml = $this->stripAttribute($xml, [self::INDEX_ATTRIBUTE]);
+        $xml = $this->stripAttributes($xml, [self::INDEX_ATTRIBUTE]);
 
         return $xml;
     }