diff --git a/src/lib_error_monad/error_monad.ml b/src/lib_error_monad/error_monad.ml
index fd66f785a..5c0c43fca 100644
--- a/src/lib_error_monad/error_monad.ml
+++ b/src/lib_error_monad/error_monad.ml
@@ -507,8 +507,6 @@ let () =
     Data_encoding.(obj1 (req "msg" string))
     (function
       | Exn (Failure msg) -> Some msg
-      | Exn (Unix.Unix_error (err, fn, _)) ->
-          Some ("Unix error in " ^ fn ^ ": " ^ Unix.error_message err)
       | Exn exn -> Some (Printexc.to_string exn)
       | _ -> None)
     (fun msg -> Exn (Failure msg))
diff --git a/src/lib_stdlib_unix/lwt_utils_unix.ml b/src/lib_stdlib_unix/lwt_utils_unix.ml
index 2d9d5f34c..8e1aed807 100644
--- a/src/lib_stdlib_unix/lwt_utils_unix.ml
+++ b/src/lib_stdlib_unix/lwt_utils_unix.ml
@@ -7,7 +7,19 @@
 (*                                                                        *)
 (**************************************************************************)
 
-open Error_monad
+let () =
+  register_error_kind
+    `Temporary
+    ~id:"unix_error"
+    ~title:"Unix error"
+    ~description:"An unhandled unix exception"
+    ~pp:Format.pp_print_string
+    Data_encoding.(obj1 (req "msg" string))
+    (function
+      | Exn (Unix.Unix_error (err, fn, _)) ->
+          Some ("Unix error in " ^ fn ^ ": " ^ Unix.error_message err)
+      | _ -> None)
+    (fun msg -> Exn (Failure msg))
 
 let read_bytes ?(pos = 0) ?len fd buf =
   let len = match len with None -> Bytes.length buf - pos | Some l -> l in