diff --git a/ml-proto/spec/check.ml b/ml-proto/spec/check.ml
index edc31850b8..a82c92717f 100644
--- a/ml-proto/spec/check.ml
+++ b/ml-proto/spec/check.ml
@@ -219,7 +219,7 @@ let rec check_expr c et e =
     check_expr c (Some t) e3
 
   | Unreachable ->
-    check_type None None e.at
+    ()
 
   | Host (hostop, es) ->
     let ({ins; out}, hasmem) = type_hostop hostop in