diff --git a/src/api/ppx_deriving.cppo.mli b/src/api/ppx_deriving.cppo.mli
index 81cb5b30..8a768e4d 100644
--- a/src/api/ppx_deriving.cppo.mli
+++ b/src/api/ppx_deriving.cppo.mli
@@ -1,5 +1,7 @@
 (** Public API of [ppx_deriving] executable. *)
 
+[@@@ocaml.deprecated "The ppx_deriving API is deprecated in favour of ppxlib"]
+
 open Ppxlib
 
 type tyvar = string Location.loc
diff --git a/src/runtime/ppx_deriving_runtime.cppo.mli b/src/runtime/ppx_deriving_runtime.cppo.mli
index 87674f57..23fd3445 100644
--- a/src/runtime/ppx_deriving_runtime.cppo.mli
+++ b/src/runtime/ppx_deriving_runtime.cppo.mli
@@ -2,6 +2,8 @@
     modules operating on them, so that ppx_deriving plugins operate
     in a well-defined environment. *)
 
+[@@@ocaml.deprecated "The ppx_deriving API is deprecated in favour of ppxlib"]
+
 (** {2 Predefined types} *)
 type nonrec int = int
 type nonrec char = char