diff --git a/phpstan.neon b/phpstan.neon
index 5ae6d0f28a..666c63b9c1 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,7 +1,7 @@
 includes:
 	- vendor/phpstan/phpstan/conf/config.level1.neon
 parameters:
-	memory-limit: 200000
+	memory-limit: 20000000
 	autoload_directories:
 		- tests
 	autoload_files:
diff --git a/src/PhpWord/Element/Title.php b/src/PhpWord/Element/Title.php
index 569cea925c..eb261b1f0e 100644
--- a/src/PhpWord/Element/Title.php
+++ b/src/PhpWord/Element/Title.php
@@ -61,14 +61,12 @@ class Title extends AbstractElement
      */
     public function __construct($text, $depth = 1)
     {
-        if (isset($text)) {
-            if (is_string($text)) {
-                $this->text = CommonText::toUTF8($text);
-            } elseif ($text instanceof TextRun) {
-                $this->text = $text;
-            } else {
-                throw new \InvalidArgumentException('Invalid text, should be a string or a TextRun');
-            }
+        if (is_string($text)) {
+            $this->text = CommonText::toUTF8($text);
+        } elseif ($text instanceof TextRun) {
+            $this->text = $text;
+        } else {
+            throw new \InvalidArgumentException('Invalid text, should be a string or a TextRun');
         }
 
         $this->depth = $depth;
diff --git a/src/PhpWord/Shared/Html.php b/src/PhpWord/Shared/Html.php
index a42816781a..f725c366a0 100644
--- a/src/PhpWord/Shared/Html.php
+++ b/src/PhpWord/Shared/Html.php
@@ -75,7 +75,7 @@ public static function addHtml($element, $html, $fullHTML = false, $preserveWhit
         $dom = new \DOMDocument();
         $dom->preserveWhiteSpace = $preserveWhiteSpace;
         $dom->loadXML($html);
-        self::$xpath = new \DOMXpath($dom);
+        self::$xpath = new \DOMXPath($dom);
         $node = $dom->getElementsByTagName('body');
 
         self::parseNode($node->item(0), $element);
diff --git a/src/PhpWord/Writer/Word2007/Element/Title.php b/src/PhpWord/Writer/Word2007/Element/Title.php
index 858ecfefa7..6a05a34d6f 100644
--- a/src/PhpWord/Writer/Word2007/Element/Title.php
+++ b/src/PhpWord/Writer/Word2007/Element/Title.php
@@ -47,6 +47,7 @@ public function write()
             $xmlWriter->endElement();
         }
 
+        $bookmarkRId = null;
         if ($element->getDepth() !== 0) {
             $rId = $element->getRelationId();
             $bookmarkRId = $element->getPhpWord()->addBookmark();
diff --git a/src/PhpWord/Writer/Word2007/Part/Chart.php b/src/PhpWord/Writer/Word2007/Part/Chart.php
index 17c1fd54ac..5a3ef27678 100644
--- a/src/PhpWord/Writer/Word2007/Part/Chart.php
+++ b/src/PhpWord/Writer/Word2007/Part/Chart.php
@@ -330,11 +330,11 @@ private function writeAxis(XMLWriter $xmlWriter, $type)
         $valueAxisTitle = $style->getValueAxisTitle();
 
         if ($axisType == 'c:catAx') {
-            if (isset($categoryAxisTitle)) {
+            if (!is_null($categoryAxisTitle)) {
                 $this->writeAxisTitle($xmlWriter, $categoryAxisTitle);
             }
         } elseif ($axisType == 'c:valAx') {
-            if (isset($valueAxisTitle)) {
+            if (!is_null($valueAxisTitle)) {
                 $this->writeAxisTitle($xmlWriter, $valueAxisTitle);
             }
         }
diff --git a/tests/PhpWord/Writer/HTML/ElementTest.php b/tests/PhpWord/Writer/HTML/ElementTest.php
index 90044b9293..b76ddded5d 100644
--- a/tests/PhpWord/Writer/HTML/ElementTest.php
+++ b/tests/PhpWord/Writer/HTML/ElementTest.php
@@ -70,7 +70,7 @@ public function testWriteTrackChanges()
         $text2->setTrackChange(new TrackChange(TrackChange::DELETED, 'another author', new \DateTime()));
 
         $dom = $this->getAsHTML($phpWord);
-        $xpath = new \DOMXpath($dom);
+        $xpath = new \DOMXPath($dom);
 
         $this->assertTrue($xpath->query('/html/body/p[1]/ins')->length == 1);
         $this->assertTrue($xpath->query('/html/body/p[2]/del')->length == 1);
@@ -94,7 +94,7 @@ public function testWriteColSpan()
         $cell22->addText('second cell');
 
         $dom = $this->getAsHTML($phpWord);
-        $xpath = new \DOMXpath($dom);
+        $xpath = new \DOMXPath($dom);
 
         $this->assertTrue($xpath->query('/html/body/table/tr[1]/td')->length == 1);
         $this->assertEquals('2', $xpath->query('/html/body/table/tr/td[1]')->item(0)->attributes->getNamedItem('colspan')->textContent);
@@ -123,7 +123,7 @@ public function testWriteRowSpan()
         $row3->addCell(500)->addText('third cell being spanned');
 
         $dom = $this->getAsHTML($phpWord);
-        $xpath = new \DOMXpath($dom);
+        $xpath = new \DOMXPath($dom);
 
         $this->assertTrue($xpath->query('/html/body/table/tr[1]/td')->length == 2);
         $this->assertEquals('3', $xpath->query('/html/body/table/tr[1]/td[1]')->item(0)->attributes->getNamedItem('rowspan')->textContent);
diff --git a/tests/PhpWord/_includes/XmlDocument.php b/tests/PhpWord/_includes/XmlDocument.php
index 81de7eff20..7062ebbf0b 100644
--- a/tests/PhpWord/_includes/XmlDocument.php
+++ b/tests/PhpWord/_includes/XmlDocument.php
@@ -37,9 +37,9 @@ class XmlDocument
     private $dom;
 
     /**
-     * DOMXpath object
+     * DOMXPath object
      *
-     * @var \DOMXpath
+     * @var \DOMXPath
      */
     private $xpath;
 
@@ -98,7 +98,7 @@ public function getNodeList($path, $file = 'word/document.xml')
         }
 
         if (null === $this->xpath) {
-            $this->xpath = new \DOMXpath($this->dom);
+            $this->xpath = new \DOMXPath($this->dom);
             $this->xpath->registerNamespace('w14', 'http://schemas.microsoft.com/office/word/2010/wordml');
         }