diff --git a/content/xml/document/resources/XMLPrettyPrint.xml b/content/xml/document/resources/XMLPrettyPrint.xml
index 50fa56203bc7..e8d8562114f9 100644
--- a/content/xml/document/resources/XMLPrettyPrint.xml
+++ b/content/xml/document/resources/XMLPrettyPrint.xml
@@ -65,11 +65,11 @@
           if (par.nodeName == 'td' && par.className == 'expander') {
             if (par.parentNode.className == 'expander-closed') {
               par.parentNode.className = '';
-              event.originalTarget.data = '-';
+              event.originalTarget.firstChild.data = '-';
             }
             else {
               par.parentNode.className = 'expander-closed';
-              event.originalTarget.data = '+';
+              event.originalTarget.firstChild.data = '+';
             }
           }
         } catch (e) {