1 files changed, 1 insertions, 1 deletions
diff --git a/data/lib/util.js b/data/lib/util.js
index f30ddd5..b128d48 100644
--- a/data/lib/util.js
+++ b/data/lib/util.js
@@ -247,7 +247,7 @@ function ISODateString(d) {
  * @return position of the string in the list, or -1 if none found.
  */
 function isInList(mbr, list) {
-  if (!list) {
+  if (!Array.isArray(list)) {
     return false;
   }
   return (list.indexOf(mbr) !== -1);