diff --git a/lib/check.ml b/lib/check.ml
index 79d28f2..329b970 100644
--- a/lib/check.ml
+++ b/lib/check.ml
@@ -5550,7 +5550,7 @@ and named_call ctx ~want loc name args =
      mechanism behind it, since neither backend needs the number early. *)
   | "filled" | "dead-beef" ->
     let is_byte = String.equal name "filled" in
-    if is_byte then arity loc name 1 args
+    if is_byte then arity ctx loc name 1 args
     else if List.length args > 1 then
       fail loc "%s takes the pattern or nothing at all, given %d arguments"
         name (List.length args);