diff --git a/samples/Sample_02_TabStops.php b/samples/Sample_02_TabStops.php
index df2ec8b3..dbed59a3 100755
--- a/samples/Sample_02_TabStops.php
+++ b/samples/Sample_02_TabStops.php
@@ -28,9 +28,9 @@ $phpWord->addParagraphStyle('centerTab', array(
 $section = $phpWord->addSection();
 
 // Add listitem elements
-$section->addText("Multiple Tabs:\tOne\tTwo\tThree", NULL, 'multipleTab');
-$section->addText("Left Aligned\tRight Aligned", NULL, 'rightTab');
-$section->addText("\tCenter Aligned",            NULL, 'centerTab');
+$section->addText("Multiple Tabs:\tOne\tTwo\tThree", null, 'multipleTab');
+$section->addText("Left Aligned\tRight Aligned", null, 'rightTab');
+$section->addText("\tCenter Aligned",            null, 'centerTab');
 
 // Save file
 $name = basename(__FILE__, '.php');
diff --git a/src/PhpWord/Style/Tab.php b/src/PhpWord/Style/Tab.php
index c28d8923..e9c044f1 100644
--- a/src/PhpWord/Style/Tab.php
+++ b/src/PhpWord/Style/Tab.php
@@ -75,7 +75,7 @@ class Tab extends AbstractStyle
      *
      * @param string $val Defaults to 'clear' if value is not possible.
      * @param int $position Must be an integer; otherwise defaults to 0.
-     * @param string $leader Defaults to NULL if value is not possible.
+     * @param string $leader Defaults to null if value is not possible.
      */
     public function __construct($val = null, $position = 0, $leader = null)
     {
@@ -85,7 +85,7 @@ class Tab extends AbstractStyle
         // Default to 0 if the position is non-numeric
         $this->position = (is_numeric($position)) ? intval($position) : 0;
 
-        // Default to NULL if no tab leader
+        // Default to null if no tab leader
         $this->leader = (self::isLeaderType($leader)) ? $leader : null;
     }