diff --git a/sledge/src/llair/typ.ml b/sledge/src/llair/typ.ml
index 615cb94ed..f45d062cb 100644
--- a/sledge/src/llair/typ.ml
+++ b/sledge/src/llair/typ.ml
@@ -58,10 +58,9 @@ let pp_defn fs = function
 (** Invariants *)
 
 let is_sized = function
-  | Function _ | Opaque _ -> false
+  | Function _ -> false
   | Integer _ | Float _ | Pointer _ | Array _ | Tuple _ | Struct _ -> true
-
-let is_sized_or_opaque = function Opaque _ -> true | t -> is_sized t
+  | Opaque _ -> (* optimistically assume linking will make it sized *) true
 
 let invariant t =
   Invariant.invariant [%here] t [%sexp_of: t]
@@ -70,9 +69,8 @@ let invariant t =
   | Function {return; args} ->
       assert (Option.for_all ~f:is_sized return) ;
       assert (Vector.for_all ~f:is_sized args)
-  | Array {elt} -> assert (is_sized_or_opaque elt)
-  | Tuple {elts} | Struct {elts} ->
-      assert (Vector.for_all ~f:is_sized_or_opaque elts)
+  | Array {elt} -> assert (is_sized elt)
+  | Tuple {elts} | Struct {elts} -> assert (Vector.for_all ~f:is_sized elts)
   | Integer {bits} | Float {bits} -> assert (bits > 0)
   | Pointer _ | Opaque _ -> assert true