diff --git a/js/spniBehaviour.js b/js/spniBehaviour.js
index abd8a67820de4441ac695df5323ac7d604e4a58e..f0a50f06e8cf377fa4d44a6c44cbddc7716445c5 100644
--- a/js/spniBehaviour.js
+++ b/js/spniBehaviour.js
@@ -710,6 +710,7 @@ function parseStyleSpecifiers (str) {
 function parseInterval (str) {
     if (!str) return undefined;
     var pieces = str.split("-");
+    if (pieces.length > 2) return null;
     var min = pieces[0].trim() == "" ? null : parseInt(pieces[0], 10);
     if (isNaN(min)) return null;
     var max = pieces.length == 1 ? min