diff --git a/.github/workflows/php.yml b/.github/workflows/php.yml
index 6fc683df..705d16c8 100644
--- a/.github/workflows/php.yml
+++ b/.github/workflows/php.yml
@@ -43,7 +43,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        php-versions: ['7.3', '7.4', '8.0', '8.1', '8.2']
+        php-versions: ['7.3', '7.4', '8.0', '8.1', '8.2', '8.3']
     steps:
       - uses: actions/checkout@v3
 
diff --git a/README.md b/README.md
index 791e518f..5501ad15 100644
--- a/README.md
+++ b/README.md
@@ -28,7 +28,7 @@ Contributions are very welcome. [Find out how to contribute](#contributing).
 
 PHP-SVG is free of dependencies. All it needs is a PHP installation satisfying the following requirements:
 
-* PHP version 7.3 or newer. This library is tested against all versions up to (and including) PHP 8.2.
+* PHP version 7.3 or newer. This library is tested against all versions up to (and including) PHP 8.3.
 * If you wish to load SVG files, or strings containing SVG code, you need to have the
   ['simplexml' PHP extension](https://www.php.net/manual/en/book.simplexml.php).
 * If you wish to use the rasterization feature for converting SVGs to raster images (PNGs, JPEGs, ...), you need to
diff --git a/src/Rasterization/Renderers/MultiPassRenderer.php b/src/Rasterization/Renderers/MultiPassRenderer.php
index 8876f810..8ddaa2f7 100644
--- a/src/Rasterization/Renderers/MultiPassRenderer.php
+++ b/src/Rasterization/Renderers/MultiPassRenderer.php
@@ -164,7 +164,7 @@ private static function prepareColor(?string $color, SVGNode $context, float $sp
         $opacity = self::calculateTotalOpacity($context) * $specificOpacity;
         $a = 127 - $opacity * (int) ($color[3] * 127 / 255);
 
-        return $rgb | ($a << 24);
+        return $rgb | ((int)$a << 24);
     }
 
     /**
diff --git a/tests/Rasterization/Path/ArcApproximatorTest.php b/tests/Rasterization/Path/ArcApproximatorTest.php
index 12bf4535..75efdbea 100644
--- a/tests/Rasterization/Path/ArcApproximatorTest.php
+++ b/tests/Rasterization/Path/ArcApproximatorTest.php
@@ -143,7 +143,7 @@ public function testApproximateRadiusScaling()
         $this->assertEqualsWithDelta(20, $result[$n - 1][0], 0.1);
         $this->assertEqualsWithDelta(10, $result[$n - 1][1], 0.1);
         // test some point roughly in the middle
-        $this->assertEqualsWithDelta(15, $result[$n / 2][0], 1);
-        $this->assertEqualsWithDelta(15, $result[$n / 2][1], 1);
+        $this->assertEqualsWithDelta(15, $result[(int)($n / 2)][0], 1);
+        $this->assertEqualsWithDelta(15, $result[(int)($n / 2)][1], 1);
     }
 }
diff --git a/tests/Reading/SVGReaderTest.php b/tests/Reading/SVGReaderTest.php
index 862c91eb..a9fb7bbc 100644
--- a/tests/Reading/SVGReaderTest.php
+++ b/tests/Reading/SVGReaderTest.php
@@ -17,6 +17,8 @@ class SVGReaderTest extends \PHPUnit\Framework\TestCase
     private $xmlUnknown;
     private $xmlValue;
     private $xmlEntities;
+    private $xmlNoXmlns;
+    private $xmlOnlyOtherXmlns;
 
     public function setUp(): void
     {