diff --git a/R/util.R b/R/util.R
index 50129a7..66ee3be 100644
--- a/R/util.R
+++ b/R/util.R
@@ -36,6 +36,7 @@
 xml_tpart <- function(x, part) {
   xchildren <- xml_children(x)
   children_names <- xml_name(xchildren)
+  if(!part %in% children_names) return(NULL)
   return(xchildren[[which(children_names == part)]])
 }