diff --git a/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs b/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
index 495c46a..371fbbd 100644
--- a/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
+++ b/Jellyfin.Plugin.SmartPlaylist/Lisp/Interpreter.cs
@@ -182,13 +182,21 @@ namespace Jellyfin.Plugin.SmartPlaylist.Lisp {
         private static Expression _invoke(IEnumerable<Expression> args) {
             Object o = (Object) args.First();
             String s = (String) args.Skip(1).First();
-            Cons l = (Cons) args.Skip(2).First();
+            IEnumerable<Expression> l;
+            if (args.Skip(2).First() is Boolean lb && lb == Boolean.FALSE) {
+                l = new List<Expression>();
+            } else if (args.Skip(2).First() is Cons lc) {
+                l = lc.ToList();
+            } else {
+                throw new ApplicationException($"Expected a list of arguments, got {args.Skip(2).First()}");
+            }
+
             IList<Expression> r = new List<Expression>();
             MethodInfo? mi = o.Value().GetType().GetMethod(s.Value());
             if (mi == null) {
                 throw new ApplicationException($"{o.Value()} has not method {s.Value()}");
             }
-            object?[]? l_ = l.ToList().Select<Expression, object?>(x => {
+            object?[]? l_ = l.Select<Expression, object?>(x => {
                 switch (x) {
                     case Integer s:
                         return s.Value();