diff --git a/src/ocaml/typing/magic_numbers.ml b/src/ocaml/typing/magic_numbers.ml
index f453cc861..e994e4b73 100644
--- a/src/ocaml/typing/magic_numbers.ml
+++ b/src/ocaml/typing/magic_numbers.ml
@@ -46,6 +46,7 @@ module Cmi = struct
     | "Caml1999I529" -> Some "5.1.1minus-14"
     | "Caml1999I530" -> Some "5.1.1minus-16"
     | "Caml1999I531" -> Some "5.1.1minus-17"
+    | "Caml1999I532" -> Some "5.1.1minus-18"
     | "Caml1999I032" -> Some "5.0"
     | "Caml1999I033" -> Some "5.1"
     | _ -> None
diff --git a/src/ocaml/utils/config.ml b/src/ocaml/utils/config.ml
index 339c9f08b..a00ac1a0f 100644
--- a/src/ocaml/utils/config.ml
+++ b/src/ocaml/utils/config.ml
@@ -32,28 +32,28 @@ let version = Sys.ocaml_version
 
 let flambda = false
 
-let exec_magic_number = "Caml1999X531"
+let exec_magic_number = "Caml1999X532"
     (* exec_magic_number is duplicated in runtime/caml/exec.h *)
 and cmi_magic_number =
   (* When bumping this number, be sure to also update ../typing/magic_numbers.ml *)
-  "Caml1999I531"
-and cmo_magic_number = "Caml1999O531"
-and cma_magic_number = "Caml1999A531"
+  "Caml1999I532"
+and cmo_magic_number = "Caml1999O532"
+and cma_magic_number = "Caml1999A532"
 and cmx_magic_number =
   if flambda then
-    "Caml2021y532"
+    "Caml2021y533"
   else
-    "Caml2021Y531"
+    "Caml2021Y532"
 and cmxa_magic_number =
   if flambda then
-    "Caml2021z532"
+    "Caml2021z533"
   else
-    "Caml2021Z531"
+    "Caml2021Z532"
 and ast_impl_magic_number = "Caml1999M033"
 and ast_intf_magic_number = "Caml1999N033"
-and cmxs_magic_number = "Caml1999D531"
-and cmt_magic_number = "Caml1999T531"
-and cms_magic_number = "Caml1999S531"
+and cmxs_magic_number = "Caml1999D532"
+and cmt_magic_number = "Caml1999T532"
+and cms_magic_number = "Caml1999S532"
 
 let interface_suffix = ref ".mli"
 
diff --git a/upstream/ocaml_flambda/base-rev.txt b/upstream/ocaml_flambda/base-rev.txt
index c1bdbbfad..5f2018080 100644
--- a/upstream/ocaml_flambda/base-rev.txt
+++ b/upstream/ocaml_flambda/base-rev.txt
@@ -1 +1 @@
-44e40db5ff117daf29689e14a80f156951b92598
+70ec392f795f68d1ec17c7889a0a6ff6c853e11a
diff --git a/upstream/ocaml_flambda/utils/config.common.ml b/upstream/ocaml_flambda/utils/config.common.ml
index bcf46fda0..a0a185201 100644
--- a/upstream/ocaml_flambda/utils/config.common.ml
+++ b/upstream/ocaml_flambda/utils/config.common.ml
@@ -31,28 +31,28 @@ let standard_library =
 (* When artifacts are incompatible with upstream OCaml, ocaml-jst uses
    magic numbers ending in 5xx. (The AST remains
    compatible, so use upstream numbers) *)
-let exec_magic_number = "Caml1999X531"
+let exec_magic_number = "Caml1999X532"
     (* exec_magic_number is duplicated in runtime/caml/exec.h *)
-and cmi_magic_number = "Caml1999I531"
-and cmo_magic_number = "Caml1999O531"
-and cma_magic_number = "Caml1999A531"
+and cmi_magic_number = "Caml1999I532"
+and cmo_magic_number = "Caml1999O532"
+and cma_magic_number = "Caml1999A532"
 and cmx_magic_number =
   if flambda || flambda2 then
-    "Caml2021y532"
+    "Caml2021y533"
   else
-    "Caml2021Y531"
+    "Caml2021Y532"
 and cmxa_magic_number =
   if flambda || flambda2 then
-    "Caml2021z532"
+    "Caml2021z533"
   else
-    "Caml2021Z531"
+    "Caml2021Z532"
 and ast_impl_magic_number = "Caml1999M033"
 and ast_intf_magic_number = "Caml1999N033"
-and cmxs_magic_number = "Caml1999D531"
-and cmt_magic_number = "Caml1999T531"
-and cms_magic_number = "Caml1999S531"
-and linear_magic_number = "Caml1999L531"
-and cfg_magic_number = "Caml2021G531"
+and cmxs_magic_number = "Caml1999D532"
+and cmt_magic_number = "Caml1999T532"
+and cms_magic_number = "Caml1999S532"
+and linear_magic_number = "Caml1999L532"
+and cfg_magic_number = "Caml2021G532"
 
 let safe_string = true
 let default_safe_string = true