diff --git a/CHANGES.md b/CHANGES.md
index be533596c..efb704fe2 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,4 +1,4 @@
-# Unreleased
+# 1.20.1
 
 ## Fixes
 
diff --git a/dune-project b/dune-project
index d47f64c70..b950df45d 100644
--- a/dune-project
+++ b/dune-project
@@ -45,7 +45,7 @@ possible and does not make any assumptions about IO.
  (description "An LSP server for OCaml.")
  (depends
   yojson
-  base
+  (base (>= v0.16.0))
   (lsp (= :version))
   (jsonrpc (= :version))
   (re (>= 1.5.0))
@@ -55,7 +55,7 @@ possible and does not make any assumptions about IO.
   dyn
   stdune
   (fiber (and (>= 3.1.1) (< 4.0.0)))
-  (ocaml (>= 5.2.0))
+  (ocaml (and (>= 5.2.0) (< 5.3)))
   xdg
   ordering
   dune-build-info
diff --git a/ocaml-lsp-server.opam b/ocaml-lsp-server.opam
index 9651f1fa2..b0e803e0b 100644
--- a/ocaml-lsp-server.opam
+++ b/ocaml-lsp-server.opam
@@ -21,7 +21,7 @@ bug-reports: "https://github.com/ocaml/ocaml-lsp/issues"
 depends: [
   "dune" {>= "3.0"}
   "yojson"
-  "base"
+  "base" {>= "v0.16.0"}
   "lsp" {= version}
   "jsonrpc" {= version}
   "re" {>= "1.5.0"}
@@ -31,7 +31,7 @@ depends: [
   "dyn"
   "stdune"
   "fiber" {>= "3.1.1" & < "4.0.0"}
-  "ocaml" {>= "5.2.0"}
+  "ocaml" {>= "5.2.0" & < "5.3"}
   "xdg"
   "ordering"
   "dune-build-info"