diff --git a/chsdi/templates/htmlpopup/base.mako b/chsdi/templates/htmlpopup/base.mako
index 471287d2d2..ece29faa76 100644
--- a/chsdi/templates/htmlpopup/base.mako
+++ b/chsdi/templates/htmlpopup/base.mako
@@ -79,15 +79,15 @@
             <td class="cell-left"></td>
             <td>
           % endif
-            % if timestamp == None:
+            % if timestamp is None:
               <a href="${''.join((c['baseUrl'], '#/map?layers=', c['layerBodId'], '@features=', str(c['featureId']), '&lang=', lang, '&topic=', topic))}" target="_blank">
                 ${_('Link to object')}
               </a>
             % else:
-            % endif
-              <a href="${''.join((c['baseUrl'], '#/map?layers=', c['layerBodId'], '@features=', str(c['featureId']), '@year=', timestamp[:4], '&lang=', lang, '&topic=', topic))}" target="_blank">
+              <a href="${''.join((c['baseUrl'], '#/map?layers=', c['layerBodId'], '@features=', str(c['featureId']), '@year=', str(timestamp[:4]), '&lang=', lang, '&topic=', topic))}" target="_blank">
                 ${_('Link to object')}
               </a>
+            % endif
             </td>
           </tr>
         %endif