diff --git a/lib/Parser.js b/lib/Parser.js
index 86a535f..388f5a8 100644
--- a/lib/Parser.js
+++ b/lib/Parser.js
@@ -201,12 +201,16 @@ Parser.prototype._resUntagged = function() {
         || type === 'search'
         || type === 'capability'
         || type === 'sort') {
-      if (m[5][0] === '(')
-        val = RE_LISTCONTENT.exec(m[5])[1].split(' ');
-      else
-        val = m[5].split(' ');
-      if (type === 'search' || type === 'sort')
-        val = val.map(function(v) { return parseInt(v, 10); });
+      if (m[5]) {
+        if (m[5][0] === '(')
+          val = RE_LISTCONTENT.exec(m[5])[1].split(' ');
+        else
+          val = m[5].split(' ');
+
+        if (type === 'search' || type === 'sort')
+          val = val.map(function(v) { return parseInt(v, 10); });
+      } else
+        val = [];
     } else if (type === 'list' || type === 'lsub')
       val = parseBoxList(m[5], this._literals);
     else if (type === 'status')