diff --git a/src/PhpWord/Writer/HTML/Style/Font.php b/src/PhpWord/Writer/HTML/Style/Font.php
index 0c416e8f..33c23f7a 100644
--- a/src/PhpWord/Writer/HTML/Style/Font.php
+++ b/src/PhpWord/Writer/HTML/Style/Font.php
@@ -35,6 +35,9 @@ class Font extends AbstractStyle
     public function write()
     {
         $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Font) {
+            return;
+        }
         $css = array();
 
         $font = $style->getName();
diff --git a/src/PhpWord/Writer/HTML/Style/Image.php b/src/PhpWord/Writer/HTML/Style/Image.php
index cdb4f8a2..fcf18395 100644
--- a/src/PhpWord/Writer/HTML/Style/Image.php
+++ b/src/PhpWord/Writer/HTML/Style/Image.php
@@ -32,6 +32,9 @@ class Image extends AbstractStyle
     public function write()
     {
         $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Image) {
+            return;
+        }
         $css = array();
 
         $css['width'] = $this->getValueIf($style->getWidth(), $style->getWidth() . 'px');
diff --git a/src/PhpWord/Writer/HTML/Style/Paragraph.php b/src/PhpWord/Writer/HTML/Style/Paragraph.php
index 27618061..cc3ad785 100644
--- a/src/PhpWord/Writer/HTML/Style/Paragraph.php
+++ b/src/PhpWord/Writer/HTML/Style/Paragraph.php
@@ -34,6 +34,9 @@ class Paragraph extends AbstractStyle
     public function write()
     {
         $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Paragraph) {
+            return;
+        }
         $css = array();
 
         // Alignment
diff --git a/src/PhpWord/Writer/ODText/Style/Font.php b/src/PhpWord/Writer/ODText/Style/Font.php
index 1a6d4fc0..eb96946c 100644
--- a/src/PhpWord/Writer/ODText/Style/Font.php
+++ b/src/PhpWord/Writer/ODText/Style/Font.php
@@ -34,7 +34,8 @@ class Font extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Font) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/ODText/Style/Paragraph.php b/src/PhpWord/Writer/ODText/Style/Paragraph.php
index 143627cd..e5f52cfe 100644
--- a/src/PhpWord/Writer/ODText/Style/Paragraph.php
+++ b/src/PhpWord/Writer/ODText/Style/Paragraph.php
@@ -34,7 +34,8 @@ class Paragraph extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Paragraph) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Cell.php b/src/PhpWord/Writer/Word2007/Style/Cell.php
index 76c347f0..c6e21625 100644
--- a/src/PhpWord/Writer/Word2007/Style/Cell.php
+++ b/src/PhpWord/Writer/Word2007/Style/Cell.php
@@ -31,7 +31,8 @@ class Cell extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Cell) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Font.php b/src/PhpWord/Writer/Word2007/Style/Font.php
index 5965d5a4..851bca22 100644
--- a/src/PhpWord/Writer/Word2007/Style/Font.php
+++ b/src/PhpWord/Writer/Word2007/Style/Font.php
@@ -57,7 +57,8 @@ class Font extends AbstractStyle
      */
     private function writeStyle()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Font) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Image.php b/src/PhpWord/Writer/Word2007/Style/Image.php
index f9338759..a891625b 100644
--- a/src/PhpWord/Writer/Word2007/Style/Image.php
+++ b/src/PhpWord/Writer/Word2007/Style/Image.php
@@ -38,9 +38,11 @@ class Image extends AbstractStyle
      */
     public function write()
     {
-        if (!is_null($this->getStyle())) {
-            $this->writeStyle();
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Image) {
+            return;
         }
+        $this->writeStyle();
     }
 
     /**
diff --git a/src/PhpWord/Writer/Word2007/Style/Indentation.php b/src/PhpWord/Writer/Word2007/Style/Indentation.php
index 797179b7..f9bb696f 100644
--- a/src/PhpWord/Writer/Word2007/Style/Indentation.php
+++ b/src/PhpWord/Writer/Word2007/Style/Indentation.php
@@ -29,7 +29,8 @@ class Indentation extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Indentation) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/LineNumbering.php b/src/PhpWord/Writer/Word2007/Style/LineNumbering.php
index c4c1216b..b3c103b6 100644
--- a/src/PhpWord/Writer/Word2007/Style/LineNumbering.php
+++ b/src/PhpWord/Writer/Word2007/Style/LineNumbering.php
@@ -31,7 +31,8 @@ class LineNumbering extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\LineNumbering) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/MarginBorder.php b/src/PhpWord/Writer/Word2007/Style/MarginBorder.php
index 8f7c1c00..28cf1224 100644
--- a/src/PhpWord/Writer/Word2007/Style/MarginBorder.php
+++ b/src/PhpWord/Writer/Word2007/Style/MarginBorder.php
@@ -29,14 +29,14 @@ class MarginBorder extends AbstractStyle
      *
      * @var int[]
      */
-    private $sizes;
+    private $sizes = array();
 
     /**
      * Colors
      *
      * @var string[]
      */
-    private $colors;
+    private $colors = array();
 
     /**
      * Other attributes
diff --git a/src/PhpWord/Writer/Word2007/Style/Paragraph.php b/src/PhpWord/Writer/Word2007/Style/Paragraph.php
index 7056028a..88a75845 100644
--- a/src/PhpWord/Writer/Word2007/Style/Paragraph.php
+++ b/src/PhpWord/Writer/Word2007/Style/Paragraph.php
@@ -66,7 +66,8 @@ class Paragraph extends AbstractStyle
      */
     private function writeStyle()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Paragraph) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Section.php b/src/PhpWord/Writer/Word2007/Style/Section.php
index b773564c..61658e03 100644
--- a/src/PhpWord/Writer/Word2007/Style/Section.php
+++ b/src/PhpWord/Writer/Word2007/Style/Section.php
@@ -31,7 +31,8 @@ class Section extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Section) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Shading.php b/src/PhpWord/Writer/Word2007/Style/Shading.php
index cc7f9364..72054c20 100644
--- a/src/PhpWord/Writer/Word2007/Style/Shading.php
+++ b/src/PhpWord/Writer/Word2007/Style/Shading.php
@@ -29,7 +29,8 @@ class Shading extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Shading) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Spacing.php b/src/PhpWord/Writer/Word2007/Style/Spacing.php
index b594d9c0..5dfb5c43 100644
--- a/src/PhpWord/Writer/Word2007/Style/Spacing.php
+++ b/src/PhpWord/Writer/Word2007/Style/Spacing.php
@@ -29,7 +29,8 @@ class Spacing extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Spacing) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Tab.php b/src/PhpWord/Writer/Word2007/Style/Tab.php
index c15d1364..865a5a9c 100644
--- a/src/PhpWord/Writer/Word2007/Style/Tab.php
+++ b/src/PhpWord/Writer/Word2007/Style/Tab.php
@@ -29,7 +29,8 @@ class Tab extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Tab) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/Table.php b/src/PhpWord/Writer/Word2007/Style/Table.php
index 7c59fd03..0a0241c3 100644
--- a/src/PhpWord/Writer/Word2007/Style/Table.php
+++ b/src/PhpWord/Writer/Word2007/Style/Table.php
@@ -36,7 +36,8 @@ class Table extends AbstractStyle
      */
     public function write()
     {
-        if (is_null($style = $this->getStyle())) {
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\Table) {
             return;
         }
         $xmlWriter = $this->getXmlWriter();
diff --git a/src/PhpWord/Writer/Word2007/Style/TextBox.php b/src/PhpWord/Writer/Word2007/Style/TextBox.php
index bb9b3a24..2bbe40e9 100644
--- a/src/PhpWord/Writer/Word2007/Style/TextBox.php
+++ b/src/PhpWord/Writer/Word2007/Style/TextBox.php
@@ -31,10 +31,12 @@ class TextBox extends Image
      */
     public function write()
     {
-        if (!is_null($this->getStyle())) {
-            $this->writeStyle();
-            $this->writeBorder();
+        $style = $this->getStyle();
+        if (!$style instanceof \PhpOffice\PhpWord\Style\TextBox) {
+            return;
         }
+        $this->writeStyle();
+        $this->writeBorder();
     }
 
     /**
diff --git a/tests/PhpWord/Tests/Writer/HTML/StyleTest.php b/tests/PhpWord/Tests/Writer/HTML/StyleTest.php
new file mode 100644
index 00000000..8af1e479
--- /dev/null
+++ b/tests/PhpWord/Tests/Writer/HTML/StyleTest.php
@@ -0,0 +1,39 @@
+<?php
+/**
+ * This file is part of PHPWord - A pure PHP library for reading and writing
+ * word processing documents.
+ *
+ * PHPWord is free software distributed under the terms of the GNU Lesser
+ * General Public License version 3 as published by the Free Software Foundation.
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code. For the full list of
+ * contributors, visit https://github.com/PHPOffice/PHPWord/contributors.
+ *
+ * @link        https://github.com/PHPOffice/PHPWord
+ * @copyright   2010-2014 PHPWord contributors
+ * @license     http://www.gnu.org/licenses/lgpl.txt LGPL version 3
+ */
+namespace PhpOffice\PhpWord\Tests\Writer\HTML;
+
+use PhpOffice\PhpWord\Shared\XMLWriter;
+
+/**
+ * Test class for PhpOffice\PhpWord\Writer\HTML\Style subnamespace
+ */
+class StyleTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Test empty styles
+     */
+    public function testEmptyStyles()
+    {
+        $styles = array('Font', 'Paragraph', 'Image');
+        foreach ($styles as $style) {
+            $objectClass = 'PhpOffice\\PhpWord\\Writer\\HTML\\Style\\' . $style;
+            $object = new $objectClass();
+
+            $this->assertEquals('', $object->write());
+        }
+    }
+}
diff --git a/tests/PhpWord/Tests/Writer/ODText/StyleTest.php b/tests/PhpWord/Tests/Writer/ODText/StyleTest.php
new file mode 100644
index 00000000..387accfc
--- /dev/null
+++ b/tests/PhpWord/Tests/Writer/ODText/StyleTest.php
@@ -0,0 +1,41 @@
+<?php
+/**
+ * This file is part of PHPWord - A pure PHP library for reading and writing
+ * word processing documents.
+ *
+ * PHPWord is free software distributed under the terms of the GNU Lesser
+ * General Public License version 3 as published by the Free Software Foundation.
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code. For the full list of
+ * contributors, visit https://github.com/PHPOffice/PHPWord/contributors.
+ *
+ * @link        https://github.com/PHPOffice/PHPWord
+ * @copyright   2010-2014 PHPWord contributors
+ * @license     http://www.gnu.org/licenses/lgpl.txt LGPL version 3
+ */
+namespace PhpOffice\PhpWord\Tests\Writer\ODText;
+
+use PhpOffice\PhpWord\Shared\XMLWriter;
+
+/**
+ * Test class for PhpOffice\PhpWord\Writer\ODText\Style subnamespace
+ */
+class StyleTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Test empty styles
+     */
+    public function testEmptyStyles()
+    {
+        $styles = array('Font', 'Paragraph');
+        foreach ($styles as $style) {
+            $objectClass = 'PhpOffice\\PhpWord\\Writer\\ODText\\Style\\' . $style;
+            $xmlWriter = new XMLWriter();
+            $object = new $objectClass($xmlWriter);
+            $object->write();
+
+            $this->assertEquals('', $xmlWriter->getData());
+        }
+    }
+}
diff --git a/tests/PhpWord/Tests/Writer/RTF/StyleTest.php b/tests/PhpWord/Tests/Writer/RTF/StyleTest.php
new file mode 100644
index 00000000..8b4a4441
--- /dev/null
+++ b/tests/PhpWord/Tests/Writer/RTF/StyleTest.php
@@ -0,0 +1,39 @@
+<?php
+/**
+ * This file is part of PHPWord - A pure PHP library for reading and writing
+ * word processing documents.
+ *
+ * PHPWord is free software distributed under the terms of the GNU Lesser
+ * General Public License version 3 as published by the Free Software Foundation.
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code. For the full list of
+ * contributors, visit https://github.com/PHPOffice/PHPWord/contributors.
+ *
+ * @link        https://github.com/PHPOffice/PHPWord
+ * @copyright   2010-2014 PHPWord contributors
+ * @license     http://www.gnu.org/licenses/lgpl.txt LGPL version 3
+ */
+namespace PhpOffice\PhpWord\Tests\Writer\RTF;
+
+use PhpOffice\PhpWord\Shared\XMLWriter;
+
+/**
+ * Test class for PhpOffice\PhpWord\Writer\RTF\Style subnamespace
+ */
+class StyleTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Test empty styles
+     */
+    public function testEmptyStyles()
+    {
+        $styles = array('Font', 'Paragraph');
+        foreach ($styles as $style) {
+            $objectClass = 'PhpOffice\\PhpWord\\Writer\\RTF\\Style\\' . $style;
+            $object = new $objectClass();
+
+            $this->assertEquals('', $object->write());
+        }
+    }
+}
diff --git a/tests/PhpWord/Tests/Writer/Word2007/StyleTest.php b/tests/PhpWord/Tests/Writer/Word2007/StyleTest.php
new file mode 100644
index 00000000..97a6c6bd
--- /dev/null
+++ b/tests/PhpWord/Tests/Writer/Word2007/StyleTest.php
@@ -0,0 +1,44 @@
+<?php
+/**
+ * This file is part of PHPWord - A pure PHP library for reading and writing
+ * word processing documents.
+ *
+ * PHPWord is free software distributed under the terms of the GNU Lesser
+ * General Public License version 3 as published by the Free Software Foundation.
+ *
+ * For the full copyright and license information, please read the LICENSE
+ * file that was distributed with this source code. For the full list of
+ * contributors, visit https://github.com/PHPOffice/PHPWord/contributors.
+ *
+ * @link        https://github.com/PHPOffice/PHPWord
+ * @copyright   2010-2014 PHPWord contributors
+ * @license     http://www.gnu.org/licenses/lgpl.txt LGPL version 3
+ */
+namespace PhpOffice\PhpWord\Tests\Writer\Word2007;
+
+use PhpOffice\PhpWord\Shared\XMLWriter;
+
+/**
+ * Test class for PhpOffice\PhpWord\Writer\Word2007\Style subnamespace
+ */
+class StyleTest extends \PHPUnit_Framework_TestCase
+{
+    /**
+     * Test empty styles
+     */
+    public function testEmptyStyles()
+    {
+        $styles = array(
+            'Cell', 'Font', 'Image', 'Indentation', 'LineNumbering',
+            'Paragraph', 'Section', 'Shading', 'Spacing', 'Tab', 'Table', 'TextBox'
+        );
+        foreach ($styles as $style) {
+            $objectClass = 'PhpOffice\\PhpWord\\Writer\\Word2007\\Style\\' . $style;
+            $xmlWriter = new XMLWriter();
+            $object = new $objectClass($xmlWriter);
+            $object->write();
+
+            $this->assertEquals('', $xmlWriter->getData());
+        }
+    }
+}