diff --git a/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs b/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
index c713d79..340cde0 100644
--- a/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
+++ b/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
@@ -47,6 +47,21 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
             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["reverse"] = e.eval(
+                """
+                (lambda
+                  (lst)
+                  (let
+                    (rev-helper
+                     (lambda
+                      (l acc)
+                      (if
+                        (null l)
+                        acc
+                        (rev-helper (cdr l) (cons (car l) acc)))))
+                    (rev-helper lst '())))
+                """
+            );
             this["qsort"] = e.eval(
                 """
                 (lambda
@@ -418,7 +433,7 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
             Executor new_e = new Executor(new SubEnvironment(e.environment), e.builtins, e.builtinsLater);
             foreach (var pair in args.SkipLast(1)) {
                 if (pair is not Cons pair_cons) {
-                    throw new ApplicationException("No expression for let*");
+                    throw new ApplicationException($"All arguments but the last have to be a list of two items, got {pair}");
                 }
                 Symbol refname = (Symbol) pair_cons.Item1;
                 Expression exp = ((Cons) pair_cons.Item2).Item1;
@@ -431,7 +446,7 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
             List<(Symbol, Expression)> vars = new List<(Symbol, Expression)>();
             foreach (var pair in args.SkipLast(1)) {
                 if (pair is not Cons pair_cons) {
-                    throw new ApplicationException("");
+                    throw new ApplicationException($"All arguments but the last have to be a list of two items, got {pair}");
                 }
                 Symbol refname = (Symbol) pair_cons.Item1;
                 Expression exp_ = ((Cons) pair_cons.Item2).Item1;
@@ -447,7 +462,7 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
             if (args.First() is Cons proc_args_) { proc_args = proc_args_.ToList().Select(x => (Symbol) x); }
             else if (args.First() == Boolean.FALSE) { proc_args = new List<Symbol>(); }
             else {
-                throw new ApplicationException("");
+                throw new ApplicationException($"Expexted an argument list, but got {args.First()}");
             }
             return new Procedure(proc_args, args.Skip(1).First(), true);
         }
@@ -456,7 +471,7 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
             if (args.First() is Cons proc_args_) { proc_args = proc_args_.ToList().Select(x => (Symbol) x); }
             else if (args.First() == Boolean.FALSE) { proc_args = new List<Symbol>(); }
             else {
-                throw new ApplicationException("");
+                throw new ApplicationException($"Expexted an argument list, but got {args.First()}");
             }
             return new Procedure(proc_args, args.Skip(1).First(), false);
         }