diff --git rdfx.terms.inc rdfx.terms.inc
index 9dc9914..d7fd0dd 100755
--- rdfx.terms.inc
+++ rdfx.terms.inc
@@ -133,7 +133,7 @@ function _rdfx_save_vocabulary($main_ns, $main_ns_prefix, $vocabulary) {
       $query = db_merge('rdfx_namespaces')
         ->key(array('gid' => $gid, 'uri' => $namespace))
         ->fields(array('uri' => $namespace, 'prefix' => $prefix, 'gid' => $gid))
-        ->update(array('prefix' => $prefix));
+        ->updateFields(array('prefix' => $prefix));
       $status = $query->execute();
     }
   }