diff --git a/libraries/opendocument.lib.php b/libraries/opendocument.lib.php
index b1325034dc..08ff2b16b7 100644
--- a/libraries/opendocument.lib.php
+++ b/libraries/opendocument.lib.php
@@ -19,6 +19,7 @@ $GLOBALS['OpenDocumentNS']
     . 'xmlns:text="urn:oasis:names:tc:opendocument:xmlns:text:1.0" '
     . 'xmlns:table="urn:oasis:names:tc:opendocument:xmlns:table:1.0" '
     . 'xmlns:style="urn:oasis:names:tc:opendocument:xmlns:style:1.0" '
+    . 'xmlns:number="urn:oasis:names:tc:opendocument:xmlns:datastyle:1.0" '
     . 'xmlns:fo="urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0" ';
 
 /**