diff --git a/src/passes/11-spilling/errors.ml b/src/passes/11-spilling/errors.ml
index 93545afd3..eef709b4f 100644
--- a/src/passes/11-spilling/errors.ml
+++ b/src/passes/11-spilling/errors.ml
@@ -54,7 +54,7 @@ let rec error_ppformat : display_format:string display_format ->
       let s = Format.asprintf "%s\n corner case: %s\n%s" loc desc (corner_case_message ()) in
       Format.pp_print_string f s
     | `Spilling_no_type_variable tv ->
-      let s = Format.asprintf "type variables can't be transpiled : %a" Var.pp tv in
+      let s = Format.asprintf "unbound type variables can't be transpiled : %a" Var.pp tv in
       Format.pp_print_string f s
     | `Spilling_unsupported_pattern_matching loc ->
       let s = Format.asprintf "%a\n unsupported pattern-matching: tuple patterns aren't supported yet" Location.pp loc in