diff --git a/ppx/distrib/ppx_distrib_expander.ml b/ppx/distrib/ppx_distrib_expander.ml
index 098b90224..ceee41dd3 100644
--- a/ppx/distrib/ppx_distrib_expander.ml
+++ b/ppx/distrib/ppx_distrib_expander.ml
@@ -11,7 +11,7 @@ open Stdppx
 open Ppxlib.Ast_builder.Default
 open Ppxlib.Ast_helper
 open Printf
-module Format = Caml.Format
+module Format = Stdlib.Format
 open Myhelpers
 
 let use_logging = false
@@ -28,12 +28,12 @@ let notify fmt =
   Printf.ksprintf
     (fun s ->
       let _cmd = Printf.sprintf "notify-send %S" s in
-      let (_ : int) = Caml.Sys.command _cmd in
+      let (_ : int) = Stdlib.Sys.command _cmd in
       ())
     fmt
 ;;
 
-let ( @@ ) = Caml.( @@ )
+let ( @@ ) = Stdlib.( @@ )
 let nolabel = Asttypes.Nolabel
 
 let mangle_construct_name name =
@@ -617,7 +617,8 @@ let make_reifier_gen ~kind is_rec tdecl : Reifier_info.t =
                              | Reify ->
                                  [%expr OCanren.Reifier.zed (OCanren.Reifier.rework ~fv:[%e fmapt])]
                              | Prj_exn -> fmapt])]
-        | _ -> failwiths ~loc:manifest.ptyp_loc "Not supported %s %d" Caml.__FILE__ Caml.__LINE__
+        | _ ->
+            failwiths ~loc:manifest.ptyp_loc "Not supported %s %d" Stdlib.__FILE__ Stdlib.__LINE__
       in
       { Reifier_info.typ = None; body = body (); name = pat_name; decl = tdecl }
   | None -> assert false
@@ -867,8 +868,8 @@ let process_main ~loc rec_ (base_tdecl, tdecl) =
           failwiths
             ~loc:base_tdecl.ptype_loc
             "%s %d Open and abstract types are not supported"
-            Caml.__FILE__
-            Caml.__LINE__)
+            Stdlib.__FILE__
+            Stdlib.__LINE__)
   in
   (* let typ_of_decl decl =
        ptyp_constr
diff --git a/ppx/fresh/ppx_fresh.ml b/ppx/fresh/ppx_fresh.ml
index 0cb00e23a..ae72fb978 100644
--- a/ppx/fresh/ppx_fresh.ml
+++ b/ppx/fresh/ppx_fresh.ml
@@ -210,14 +210,14 @@ let mapper =
               in
               ans
           | None ->
-              Caml.Format.eprintf "Can't reconstruct args of 'fresh'";
+              Stdlib.Format.eprintf "Can't reconstruct args of 'fresh'";
               { e with pexp_desc = Pexp_apply (e1, [ Nolabel, new_body ]) })
       | Pexp_apply (d, [ (_, body) ]) when is_defer d ->
           let ans = [%expr delay (fun () -> [%e self#expression body])] in
           ans
       | Pexp_apply (d, body) when is_unif d ->
           (* let loc_str =
-               Caml.Format.asprintf "%a" Selected_ast.Ast.Location.print_compact e.pexp_loc;
+               Stdlib.Format.asprintf "%a" Selected_ast.Ast.Location.print_compact e.pexp_loc;
              in
              let body = (Labelled "loc", Exp.constant (Pconst_string (loc_str,None))) :: body in *)
           Exp.apply ~loc:e.pexp_loc d body
@@ -309,7 +309,7 @@ let mapper =
       | Pexp_open (_od, ee) -> { e with pexp_desc = Pexp_open (_od, self#expression ee) }
       | Pexp_letop _ | Pexp_extension _ | Pexp_pack _ -> e
     (* | _ ->
-       Caml.Format.printf "%a\n%a\n%!" Location.print loc Pprintast.expression e;
+       Stdlib.Format.printf "%a\n%a\n%!" Location.print loc Pprintast.expression e;
        assert false*)
   end
 ;;
diff --git a/ppx/myhelpers.ml b/ppx/myhelpers.ml
index e089dc970..919cece9d 100644
--- a/ppx/myhelpers.ml
+++ b/ppx/myhelpers.ml
@@ -20,7 +20,8 @@ let extract_names =
   List.map ~f:(fun (typ, _) ->
       match typ.ptyp_desc with
       | Ptyp_var s -> s
-      | _ -> failwith (Caml.Format.asprintf "Don't know what to do with %a" Pprintast.core_type typ))
+      | _ ->
+          failwith (Stdlib.Format.asprintf "Don't know what to do with %a" Pprintast.core_type typ))
 ;;
 
 open Ppxlib.Ast_builder.Default
@@ -31,7 +32,7 @@ module Located = struct
 
   (* let mknoloc txt = { txt; loc = Location.none } *)
   let map_loc ~f l = { l with txt = f l.txt }
-  let sprintf ~loc fmt = Caml.Format.kasprintf (mk ~loc) fmt
+  let sprintf ~loc fmt = Stdlib.Format.kasprintf (mk ~loc) fmt
 end
 
 module Exp = struct
diff --git a/ppx/reify/reify_impl.ml b/ppx/reify/reify_impl.ml
index 926c2f6d0..aad843590 100644
--- a/ppx/reify/reify_impl.ml
+++ b/ppx/reify/reify_impl.ml
@@ -20,7 +20,7 @@
 open Ppxlib
 open Stdppx
 open Ppxlib.Ast_builder.Default
-module Format = Caml.Format
+module Format = Stdlib.Format
 open Myhelpers
 
 type naming =
@@ -413,7 +413,7 @@ let make_reifier_composition ~pat ?(typ = None) kind tdecl =
   let helper = reifier_of_core_type kind in
   let manifest =
     match tdecl.ptype_manifest with
-    | None -> failwiths "A type without manifest %s %d" Caml.__FILE__ Caml.__LINE__
+    | None -> failwiths "A type without manifest %s %d" Stdlib.__FILE__ Stdlib.__LINE__
     | Some m -> m
   in
   let body =
@@ -427,7 +427,8 @@ let make_reifier_composition ~pat ?(typ = None) kind tdecl =
           (Exp.ident ~loc @@ lident_of_list [ "OCanren"; "Std"; "Pair"; reifier_name ])
           [ helper ~loc l; helper ~loc r ]
     | Ptyp_tuple _ -> helper ~loc manifest
-    | _ -> failwiths ~loc "This type is not expected as manifest %s %d" Caml.__FILE__ Caml.__LINE__
+    | _ ->
+        failwiths ~loc "This type is not expected as manifest %s %d" Stdlib.__FILE__ Stdlib.__LINE__
   in
   let loc = tdecl.ptype_loc in
   let pat =