diff --git a/run.nu b/run.nu
index af30710..3cac141 100755
--- a/run.nu
+++ b/run.nu
@@ -1,8 +1,12 @@
 #!/usr/bin/env nu
 
+def complete [] {
+  ls 2023 | get names | filter { not ($in str-endswith ".in") }
+}
+
 # Run a specified AoC solution.
 def main [
-  year_day_part_ext: string # The file to run. For example `2023/1-2.py` or `2023/1-2.nix`.
+  year_day_part_ext: string@complete # The file to run. For example `2023/1-2.py` or `2023/1-2.nix`.
 ] {
   match ($year_day_part_ext | path parse | get extension) {
     "nix" => {