diff --git a/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs b/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
index 7d68941..8cb7631 100644
--- a/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
+++ b/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
@@ -46,6 +46,38 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
             this["fold"] = e.eval("(lambda (fc i l) (if (null l) i (fold fc (fc i (car l)) (cdr l))))");
             this["any"] = e.eval("(lambda (fc l) (apply or (map fc l)))");
             this["all"] = e.eval("(lambda (fc l) (apply and (map fc l)))");
+            this["append"] = e.eval("(lambda (l i) (if (null l) i (cons (car l) (append (cdr l) i))))");
+            this["qsort"] = e.eval(
+                """
+                (lambda
+                  (fc list00)
+                  (let
+                    (getpivot
+                      (lambda
+                        (list0)
+                        (car list0)))
+                    (split
+                      (lambda
+                        (list0 pivot fc h0 h1)
+                        (cond
+                          ((null list0) (list list0 pivot fc h0 h1))
+                          ((fc (car list0) pivot) (split (cdr list0) pivot fc h0 (cons (car list0) h1)))
+                          (t (split (cdr list0) pivot fc (cons (car list0) h0) h1)))))
+                    (sort
+                      (lambda
+                        (fc list0)
+                        (cond
+                          ((null list0) nil)
+                          ((null (cdr list0)) list0)
+                          (t
+                            (let*
+                              (halves (split list0 (getpivot list0) fc nil nil))
+                              (h0 (car (cdr (cdr (cdr halves)))))
+                              (h1 (car (cdr (cdr (cdr (cdr halves))))))
+                              (append (sort fc h0) (sort fc h1)))))))
+                    (sort fc list00)))
+                """
+            );
         }
     }
 
diff --git a/Tests/Tests.cs b/Tests/Tests.cs
index 4052b24..9c1b598 100644
--- a/Tests/Tests.cs
+++ b/Tests/Tests.cs
@@ -226,6 +226,8 @@ namespace Tests
             Assert.Equal("nil", e.eval("(all (lambda (x) (= 1 (% x 2))) (list 1 3 4 5))").ToString());
             Assert.Equal("nil", e.eval("(all (lambda (x) (= x 2)) nil)").ToString());
             Assert.Equal("10", e.eval("(fold (lambda (a b) (+ a b)) 0 (list 1 2 3 4))").ToString());
+            Assert.Equal("(2 3 4 5 6 7)", e.eval("(append (list 2 3 4) (list 5 6 7))").ToString());
+            Assert.Equal("(1 2 3 4 5 6 7)", e.eval("(qsort (lambda (a b) (> a b)) (list 5 4 7 3 2 6 1))").ToString());
         }
     }
 }