diff --git a/lib/common/ocaml/Makefile b/lib/common/ocaml/Makefile
index c6ce48d3..c7bb6a01 100644
--- a/lib/common/ocaml/Makefile
+++ b/lib/common/ocaml/Makefile
@@ -33,27 +33,16 @@ endif
 
 
 OCAMLBUILD=ocamlbuild -use-ocamlfind
-CAMLP4_DEFS ?=
 
 #
 # NOTE: due to a bug in older ocamlbuild versions the build-dir can NOT be absolute
 # see http://caml.inria.fr/mantis/view.php?id=5503
-#
-OCAML_VERSION := $(shell ocamlc -version)
-OCAML_MAJOR := $(shell echo $(OCAML_VERSION) | cut -f1 -d.)
-OCAMLC_MINOR := $(shell echo $(OCAML_VERSION) | cut -f2 -d.)
 # using a recent ocaml(build) version >= 4,
 # but build-dir MUST NOT contain ..
 # so use some magic here to get a normalized absolute path if PPRZLINK_DIR is not set
 PPRZLINK_DIR ?= $(realpath $(dir $(lastword $(MAKEFILE_LIST)))/../../..)
 BUILDDIR ?= $(PPRZLINK_DIR)/build/ocaml/pprzlink
 
-ifeq ($(shell test $(OCAMLC_MINOR) -ge 2; echo $$?),0)
-ifeq ($(shell test $(OCAMLC_MINOR) -ge 4; echo $$?),0)
-CAMLP4_DEFS += -DOCAML_V404
-endif
-endif
-
 INSTALL_FLAGS ?=
 # use this option leave ocamlfind ldconf file unchanged
 INSTALL_FLAGS += -ldconf ignore
@@ -62,7 +51,6 @@ ifneq ($(DESTDIR),)
 INSTALL_FLAGS += -destdir $(DESTDIR)
 endif
 
-PP_OPTS = -pp "camlp4o pa_macro.cmo $(CAMLP4_DEFS)"
 # enforce checking a clear type checking between bytes and string
 C_OPTS = -cflags -safe-string
 INSTALL_FILES = $(shell ls $(BUILDDIR)/*.so $(BUILDDIR)/*.a $(BUILDDIR)/*.mli $(BUILDDIR)/*.cm* $(BUILDDIR)/common/*.mli $(BUILDDIR)/common/*.cm*)
@@ -73,20 +61,20 @@ all: byte native
 byte: _tags META
 	@echo Build bytecode lib
 	$(Q)test -d $(BUILDDIR) || mkdir -p $(BUILDDIR)
-	$(Q)$(OCAMLBUILD) $(QUIET) $(PP_OPTS) $(C_OPTS) -build-dir $(BUILDDIR) -I common lib-pprzlink.cma
+	$(Q)$(OCAMLBUILD) $(QUIET) $(C_OPTS) -build-dir $(BUILDDIR) -I common lib-pprzlink.cma
 	$(Q)cp META $(BUILDDIR)
 
 # byte with statically linked libs
 static: _tags META
 	@echo Build bytecode lib with static linking
 	$(Q)test -d $(BUILDDIR) || mkdir -p $(BUILDDIR)
-	$(Q)$(OCAMLBUILD) $(QUIET) $(PP_OPTS) $(C_OPTS) -build-dir $(BUILDDIR) -tag static -I common lib-pprzlink.cma
+	$(Q)$(OCAMLBUILD) $(QUIET) $(C_OPTS) -build-dir $(BUILDDIR) -tag static -I common lib-pprzlink.cma
 	$(Q)cp META $(BUILDDIR)
 
 native: _tags META
 	@echo Build native lib
 	$(Q)test -d $(BUILDDIR) || mkdir -p $(BUILDDIR)
-	$(Q)$(OCAMLBUILD) $(QUIET) $(PP_OPTS) $(C_OPTS) -build-dir $(BUILDDIR) -I common lib-pprzlink.cmxa
+	$(Q)$(OCAMLBUILD) $(QUIET) $(C_OPTS) -build-dir $(BUILDDIR) -I common lib-pprzlink.cmxa
 	$(Q)cp META $(BUILDDIR)
 
 install: clean_lib byte native META
diff --git a/lib/common/ocaml/compatPL.ml b/lib/common/ocaml/compatPL.ml
deleted file mode 100644
index c6654775..00000000
--- a/lib/common/ocaml/compatPL.ml
+++ /dev/null
@@ -1,39 +0,0 @@
-(*
- * Abstract some String/Byte functions for compatibility between OCaml 3.x and 4.x
- *
- * Copyright (C) 2016 Felix Ruess <felix.ruess@gmail.com>
- *
- * This file is part of paparazzi.
- *
- * paparazzi is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * paparazzi is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with paparazzi; see the file COPYING.  If not, write to
- * the Free Software Foundation, 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- *
- *)
-
-IFDEF OCAML_V404 THEN
-let lowercase_ascii = String.lowercase_ascii
-
-let uppercase_ascii = String.uppercase_ascii
-
-let capitalize_ascii = String.capitalize_ascii
-
-ELSE
-let lowercase_ascii = String.lowercase
-
-let uppercase_ascii = String.uppercase
-
-let capitalize_ascii = String.capitalize
-
-END
diff --git a/lib/common/ocaml/compatPL.mli b/lib/common/ocaml/compatPL.mli
deleted file mode 100644
index 2b725f67..00000000
--- a/lib/common/ocaml/compatPL.mli
+++ /dev/null
@@ -1,27 +0,0 @@
-(*
- * Abstract some String/Byte functions for compatibility between OCaml 3.x and 4.x
- *
- * Copyright (C) 2016 Felix Ruess <felix.ruess@gmail.com>
- *
- * This file is part of paparazzi.
- *
- * paparazzi is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation; either version 2, or (at your option)
- * any later version.
- *
- * paparazzi is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with paparazzi; see the file COPYING.  If not, write to
- * the Free Software Foundation, 59 Temple Place - Suite 330,
- * Boston, MA 02111-1307, USA.
- *
- *)
-
-val lowercase_ascii : string -> string
-val uppercase_ascii : string -> string
-val capitalize_ascii : string -> string
diff --git a/lib/v1.0/ocaml/lib-pprzlink.mllib b/lib/v1.0/ocaml/lib-pprzlink.mllib
index c75b1721..50f35058 100644
--- a/lib/v1.0/ocaml/lib-pprzlink.mllib
+++ b/lib/v1.0/ocaml/lib-pprzlink.mllib
@@ -4,4 +4,3 @@ protocol
 pprz_transport
 pprzlog_transport
 xbee_transport
-compatPL
diff --git a/lib/v1.0/ocaml/pprzLink.ml b/lib/v1.0/ocaml/pprzLink.ml
index c3381d66..42c1389c 100644
--- a/lib/v1.0/ocaml/pprzLink.ml
+++ b/lib/v1.0/ocaml/pprzLink.ml
@@ -245,7 +245,7 @@ let scale_of_units = fun ?auto from_unit to_unit ->
         and a = try Some (Xml.attrib u "auto") with _ -> None in
         let a = match auto, a with
           | Some _, None | None, None -> "" (* No auto conversion *)
-          | Some t, Some _ | None, Some t -> CompatPL.lowercase_ascii t (* param auto is used before attribute *)
+          | Some t, Some _ | None, Some t -> String.lowercase_ascii t (* param auto is used before attribute *)
         in
         if (f = from_unit || a = "display") && (t = to_unit || a = "code") then true else false
       ) (Xml.children units_xml) in
@@ -332,14 +332,14 @@ let field_of_xml = fun xml ->
   let auc = alt_unit_coef_of_xml xml in
   let values = try Str.split pipe_regexp (Xml.attrib xml "values") with _ -> [] in
 
-  ( CompatPL.lowercase_ascii (xml_attrib xml "name"),
+  ( String.lowercase_ascii (xml_attrib xml "name"),
     { _type = t; fformat = f; alt_unit_coef = auc; enum=values })
 
 let string_of_values = fun vs ->
   String.concat " " (List.map (fun (a,v) -> sprintf "%s=%s" a (string_of_value v)) vs)
 
 let assoc = fun a vs ->
-  try List.assoc (CompatPL.lowercase_ascii a) vs with Not_found ->
+  try List.assoc (String.lowercase_ascii a) vs with Not_found ->
     failwith (sprintf "Attribute '%s' not found in '%s'" a (string_of_values vs))
 
 let float_assoc = fun (a:string) vs ->
diff --git a/lib/v2.0/ocaml/lib-pprzlink.mllib b/lib/v2.0/ocaml/lib-pprzlink.mllib
index c75b1721..50f35058 100644
--- a/lib/v2.0/ocaml/lib-pprzlink.mllib
+++ b/lib/v2.0/ocaml/lib-pprzlink.mllib
@@ -4,4 +4,3 @@ protocol
 pprz_transport
 pprzlog_transport
 xbee_transport
-compatPL
diff --git a/lib/v2.0/ocaml/pprzLink.ml b/lib/v2.0/ocaml/pprzLink.ml
index 68e94464..e897e7a1 100644
--- a/lib/v2.0/ocaml/pprzLink.ml
+++ b/lib/v2.0/ocaml/pprzLink.ml
@@ -248,7 +248,7 @@ let scale_of_units = fun ?auto from_unit to_unit ->
         and a = try Some (Xml.attrib u "auto") with _ -> None in
         let a = match auto, a with
           | Some _, None | None, None -> "" (* No auto conversion *)
-          | Some t, Some _ | None, Some t -> CompatPL.lowercase_ascii t (* param auto is used before attribute *)
+          | Some t, Some _ | None, Some t -> String.lowercase_ascii t (* param auto is used before attribute *)
         in
         if (f = from_unit || a = "display") && (t = to_unit || a = "code") then true else false
       ) (Xml.children units_xml) in
@@ -335,14 +335,14 @@ let field_of_xml = fun xml ->
   let auc = alt_unit_coef_of_xml xml in
   let values = try Str.split pipe_regexp (Xml.attrib xml "values") with _ -> [] in
 
-  ( CompatPL.lowercase_ascii (xml_attrib xml "name"),
+  ( String.lowercase_ascii (xml_attrib xml "name"),
     { _type = t; fformat = f; alt_unit_coef = auc; enum=values })
 
 let string_of_values = fun vs ->
   String.concat " " (List.map (fun (a,v) -> sprintf "%s=%s" a (string_of_value v)) vs)
 
 let assoc = fun a vs ->
-  try List.assoc (CompatPL.lowercase_ascii a) vs with Not_found ->
+  try List.assoc (String.lowercase_ascii a) vs with Not_found ->
     failwith (sprintf "Attribute '%s' not found in '%s'" a (string_of_values vs))
 
 let float_assoc = fun (a:string) vs ->
diff --git a/tools/generator/Makefile b/tools/generator/Makefile
index 2c4798fb..aedf2db4 100644
--- a/tools/generator/Makefile
+++ b/tools/generator/Makefile
@@ -28,21 +28,12 @@ OCAMLBUILD=ocamlbuild -use-ocamlfind
 #
 # NOTE: due to a bug in older ocamlbuild versions the build-dir can NOT be absolute
 # see http://caml.inria.fr/mantis/view.php?id=5503
-#
-OCAML_VERSION := $(shell ocamlc -version)
-OCAML_MAJOR := $(shell echo $(OCAML_VERSION) | cut -f1 -d.)
-ifeq ($(shell test $(OCAML_MAJOR) -lt 4; echo $$?),0)
-# need to use an old buggy ocaml(build) version: dir MUST be relative
-OCAML_LIBDIR ?= ../../build/ocaml
-BUILDDIR ?= ../../build/ocaml/gen
-else
 # using a recent ocaml(build) version without THAT particular bug,
 # but dir MUST NOT contain ..
 # so use some magic here to get a normalized absolute path if PPRZLINK_DIR is not set
 PPRZLINK_DIR ?= $(realpath $(dir $(lastword $(MAKEFILE_LIST)))/../..)
 OCAML_LIBDIR ?= $(PPRZLINK_DIR)/build/ocaml
 BUILDDIR ?= $(PPRZLINK_DIR)/build/ocaml/gen
-endif
 
 # FIXME test if pprzlink is installed in the system or try local build
 export OCAMLPATH=$(OCAML_LIBDIR)