diff --git a/lib/ast.js b/lib/ast.js
index 9bdbe7bf..e0fa6fe8 100644
--- a/lib/ast.js
+++ b/lib/ast.js
@@ -610,7 +610,13 @@ var AST_Seq = DEFNODE("Seq", "car cdr", {
         var i = array.length - 1;
         var list = array[i];
         while (--i >= 0) {
-            list = AST_Seq.cons(array[i], list);
+            var node = array[i];
+            if (node instanceof AST_Seq) {
+                node.add(list);
+                list = node;
+            } else {
+                list = AST_Seq.cons(array[i], list);
+            }
         }
         return list;
     },