diff --git a/lib/utils/version.js b/lib/utils/version.js
index d691807..6a8cf86 100644
--- a/lib/utils/version.js
+++ b/lib/utils/version.js
@@ -88,7 +88,7 @@ define(function () {
       rb = parseB.exec(b);
     }
     if (!ra && rb) { // rb doesn't get exec-ed when ra == null
-      return (parseB.exec(b)[1].split('')[0] === '~') ? 1 : -1;
+      return (rb.length > 0 && rb[1].split('')[0] === '~') ? 1 : -1;
     } else if (ra && !rb) {
       return (ra[1].split('')[0] === '~') ? -1 : 1;
     }