diff --git a/src/logging.ml b/src/logging.ml
index 77cd61598d29c2601bf1465a4283546cc66a665e..afe6c3d5132e8bebfc474208afec04f9ed67bbc6 100644
--- a/src/logging.ml
+++ b/src/logging.ml
@@ -117,4 +117,5 @@ let () =
     | Invalid_argument msg -> Fmt.pf fmt "Invalid argument: %s" msg
     | Failure msg -> Fmt.pf fmt "Failure: %s" msg
     | Sys_error msg -> Fmt.pf fmt "%s" msg
+    | Sexplib0.Sexp.Not_found_s sexp -> Sexplib0.Sexp.pp_hum fmt sexp
     | _ -> raise exn)