diff --git a/src/ErrorReporting.ml b/src/ErrorReporting.ml
index 3cdc333ec3e61b8d331670efb9643353405b7317..f97688131a7547a8d33f041e5895db2971c0bd41 100644
--- a/src/ErrorReporting.ml
+++ b/src/ErrorReporting.ml
@@ -53,7 +53,7 @@ module Make
     match Lazy.force (stack env) with
     | Nil ->
         (* If we get here, then the stack is empty, which means the parser
-           is an initial state. This should not happen. *)
+           is in an initial state. This should not happen. *)
         invalid_arg "items_current" (* TEMPORARY it DOES happen! *)
     | Cons (Element (current, _, _, _), _) ->
         (* Extract the current state out of the top stack element, and
@@ -154,7 +154,7 @@ module Make
      important because the position of the dummy token may end up in
      the explanations that we produce. *)
 
-  let investigate pos (result : _ result) =
+  let investigate pos (result : _ result) : explanation list =
     weed compare_explanations (
       foreach_terminal_but_error (fun symbol explanations ->
         match symbol with
@@ -227,4 +227,7 @@ module Make
     assert (match start with InputNeeded _ -> true | _ -> false);
     loop (wrap lexer lexbuf) { checkpoint = start; current = start }
 
+  (* TEMPORARY could also publish a list of the terminal symbols that
+     do not cause an error *)
+
 end