diff --git a/VERSION b/VERSION
index 89a99f031b6e..c30c6d2e75e7 100644
--- a/VERSION
+++ b/VERSION
@@ -1,4 +1,4 @@
-4.12.1
+4.12.2+dev0-2021-09-23
 
 # The version string is the first line of this file.
 # It must be in the format described in stdlib/sys.mli
diff --git a/configure b/configure
index 81a77e3b68a2..b1e287aed3d2 100755
--- a/configure
+++ b/configure
@@ -56,7 +56,7 @@ if test -e '.git' ; then :
   fi
 fi
 # Guess values for system-dependent variables and create Makefiles.
-# Generated by GNU Autoconf 2.69 for OCaml 4.12.1.
+# Generated by GNU Autoconf 2.69 for OCaml 4.12.2+dev0-2021-09-23.
 #
 # Report bugs to <caml-list@inria.fr>.
 #
@@ -646,8 +646,8 @@ MAKEFLAGS=
 # Identity of this package.
 PACKAGE_NAME='OCaml'
 PACKAGE_TARNAME='ocaml'
-PACKAGE_VERSION='4.12.1'
-PACKAGE_STRING='OCaml 4.12.1'
+PACKAGE_VERSION='4.12.2+dev0-2021-09-23'
+PACKAGE_STRING='OCaml 4.12.2+dev0-2021-09-23'
 PACKAGE_BUGREPORT='caml-list@inria.fr'
 PACKAGE_URL='http://www.ocaml.org'
 
@@ -1473,7 +1473,7 @@ if test "$ac_init_help" = "long"; then
   # Omit some internal or obsolete options to make the list less imposing.
   # This message is too long to be a string in the A/UX 3.1 sh.
   cat <<_ACEOF
-\`configure' configures OCaml 4.12.1 to adapt to many kinds of systems.
+\`configure' configures OCaml 4.12.2+dev0-2021-09-23 to adapt to many kinds of systems.
 
 Usage: $0 [OPTION]... [VAR=VALUE]...
 
@@ -1539,7 +1539,7 @@ fi
 
 if test -n "$ac_init_help"; then
   case $ac_init_help in
-     short | recursive ) echo "Configuration of OCaml 4.12.1:";;
+     short | recursive ) echo "Configuration of OCaml 4.12.2+dev0-2021-09-23:";;
    esac
   cat <<\_ACEOF
 
@@ -1695,7 +1695,7 @@ fi
 test -n "$ac_init_help" && exit $ac_status
 if $ac_init_version; then
   cat <<\_ACEOF
-OCaml configure 4.12.1
+OCaml configure 4.12.2+dev0-2021-09-23
 generated by GNU Autoconf 2.69
 
 Copyright (C) 2012 Free Software Foundation, Inc.
@@ -2404,7 +2404,7 @@ cat >config.log <<_ACEOF
 This file contains any messages produced by compilers while
 running configure, to aid debugging if configure makes a mistake.
 
-It was created by OCaml $as_me 4.12.1, which was
+It was created by OCaml $as_me 4.12.2+dev0-2021-09-23, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   $ $0 $@
@@ -2753,8 +2753,8 @@ ac_compiler_gnu=$ac_cv_c_compiler_gnu
 
 
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: Configuring OCaml version 4.12.1" >&5
-$as_echo "$as_me: Configuring OCaml version 4.12.1" >&6;}
+{ $as_echo "$as_me:${as_lineno-$LINENO}: Configuring OCaml version 4.12.2+dev0-2021-09-23" >&5
+$as_echo "$as_me: Configuring OCaml version 4.12.2+dev0-2021-09-23" >&6;}
 
 # Configuration variables
 
@@ -2835,7 +2835,7 @@ ac_configure="$SHELL $ac_aux_dir/configure"  # Please don't use this var.
 
 
 
-VERSION=4.12.1
+VERSION=4.12.2+dev0-2021-09-23
 
 
 # Note: This is present for the flexdll bootstrap where it exposed as the old
@@ -12647,7 +12647,7 @@ case $ocaml_cv_cc_vendor in #(
   cc_warnings='-Wall -Wdeclaration-after-statement' ;;
 esac
 
-case $enable_warn_error,4.12.1 in #(
+case $enable_warn_error,4.12.2+dev0-2021-09-23 in #(
   yes,*|,*+dev*) :
     cc_warnings="$cc_warnings $warn_error_flag" ;; #(
   *) :
@@ -16929,7 +16929,7 @@ else
   ocamldoc=ocamldoc
 fi
 
-case $enable_ocamltest,4.12.1 in #(
+case $enable_ocamltest,4.12.2+dev0-2021-09-23 in #(
   yes,*|,*+dev*) :
     ocamltest='ocamltest' ;; #(
   *) :
@@ -17649,7 +17649,7 @@ cat >>$CONFIG_STATUS <<\_ACEOF || ac_write_fail=1
 # report actual input values of CONFIG_FILES etc. instead of their
 # values after options handling.
 ac_log="
-This file was extended by OCaml $as_me 4.12.1, which was
+This file was extended by OCaml $as_me 4.12.2+dev0-2021-09-23, which was
 generated by GNU Autoconf 2.69.  Invocation command line was
 
   CONFIG_FILES    = $CONFIG_FILES
@@ -17716,7 +17716,7 @@ _ACEOF
 cat >>$CONFIG_STATUS <<_ACEOF || ac_write_fail=1
 ac_cs_config="`$as_echo "$ac_configure_args" | sed 's/^ //; s/[\\""\`\$]/\\\\&/g'`"
 ac_cs_version="\\
-OCaml config.status 4.12.1
+OCaml config.status 4.12.2+dev0-2021-09-23
 configured by $0, generated by GNU Autoconf 2.69,
   with options \\"\$ac_cs_config\\"
 
diff --git a/ocaml-variants.opam b/ocaml-variants.opam
index ff17b2841a4b..563e00477c3a 100644
--- a/ocaml-variants.opam
+++ b/ocaml-variants.opam
@@ -1,8 +1,8 @@
 opam-version: "2.0"
-version: "4.12.1"
-synopsis: "OCaml 4.12.1"
+version: "4.12.2+trunk"
+synopsis: "OCaml 4.12 maintenance version"
 depends: [
-  "ocaml" {= "4.12.1" & post}
+  "ocaml" {= "4.12.2" & post}
   "base-unix" {post}
   "base-bigarray" {post}
   "base-threads" {post}