diff --git a/src/PhpWord/Writer/ODText/Style/Paragraph.php b/src/PhpWord/Writer/ODText/Style/Paragraph.php
index 68613855..14a811a5 100644
--- a/src/PhpWord/Writer/ODText/Style/Paragraph.php
+++ b/src/PhpWord/Writer/ODText/Style/Paragraph.php
@@ -35,8 +35,8 @@ class Paragraph extends AbstractStyle
         }
         $xmlWriter = $this->getXmlWriter();
 
-        $marginTop = ($style->getSpaceBefore() ==0 ) ? '0' : round(17.6 / $style->getSpaceBefore(), 2);
-        $marginBottom = ($style->getSpaceAfter() == 0) ? '0' : round(17.6 / $style->getSpaceAfter(), 2);
+        $marginTop = (is_null($style->getSpaceBefore()) || $style->getSpaceBefore() == 0) ? '0' : round(17.6 / $style->getSpaceBefore(), 2);
+        $marginBottom = (is_null($style->getSpaceAfter()) || $style->getSpaceAfter() == 0) ? '0' : round(17.6 / $style->getSpaceAfter(), 2);
 
         $xmlWriter->startElement('style:style');
         $xmlWriter->writeAttribute('style:name', $style->getStyleName());