diff --git a/ocaml/default.nix b/ocaml/default.nix
index a78032bda..248228cfa 100644
--- a/ocaml/default.nix
+++ b/ocaml/default.nix
@@ -1280,8 +1280,8 @@ with oself;
 
   mirage-logs = osuper.mirage-logs.overrideAttrs (_: {
     src = builtins.fetchurl {
-      url = https://github.com/mirage/mirage-logs/releases/download/v2.0.0/mirage-logs-2.0.0.tbz;
-      sha256 = "086x45sijjldg1vcvf7lq23fqxrl8mbbp2ym8hja7gl6m9j759pj";
+      url = https://github.com/mirage/mirage-logs/releases/download/v2.1.0/mirage-logs-2.1.0.tbz;
+      sha256 = "1fww8q0an84wiqfwycqlv9chc52a9apf6swbiqk28h1v1jrc52mf";
     };
   });
 
diff --git a/ocaml/eio-ssl/default.nix b/ocaml/eio-ssl/default.nix
index 3a5c858f5..82994d906 100644
--- a/ocaml/eio-ssl/default.nix
+++ b/ocaml/eio-ssl/default.nix
@@ -6,8 +6,8 @@ buildDunePackage {
   src = fetchFromGitHub {
     owner = "anmonteiro";
     repo = "eio-ssl";
-    rev = "c5c9c3562baf771f7a00fa52b52dfe1f956b5489";
-    hash = "sha256-67Mjh/GmnjLMfubcXHUVXeRe2pyhezT4IPX0E7DSXEg=";
+    rev = "5e83c3ffb2200affde9d900de02f6994dd6421da";
+    hash = "sha256-rkk4OA+kq2jFuKwVtR9MRDtMXt7WYc9fBB+CgY+n6Kc=";
   };
   propagatedBuildInputs = [ ssl eio ];
 }
diff --git a/ocaml/gluten/default.nix b/ocaml/gluten/default.nix
index d4f5d22d3..aded5765f 100644
--- a/ocaml/gluten/default.nix
+++ b/ocaml/gluten/default.nix
@@ -7,8 +7,8 @@ buildDunePackage {
   src = fetchFromGitHub {
     owner = "anmonteiro";
     repo = "gluten";
-    rev = "0c672bf386047e5ce88677f3e5dfc67b7e9c04d9";
-    hash = "sha256-NDB92mTncEWr9wJ6h4Ahi6UwdKpg8BZcPxiH7lbnCH8=";
+    rev = "e8efb527eb92924793615714c973cd9ee32d490b";
+    hash = "sha256-7T2VwdNjkqMEAqHlfe0TgroOnj/O/RDdlSy3ySIzXCw=";
   };
   propagatedBuildInputs = [ bigstringaf faraday ke ];
 }
diff --git a/ocaml/melange-packages.nix b/ocaml/melange-packages.nix
index 19d60ffef..c3a0597e7 100644
--- a/ocaml/melange-packages.nix
+++ b/ocaml/melange-packages.nix
@@ -101,8 +101,8 @@ with oself;
     src = fetchFromGitHub {
       owner = "reasonml";
       repo = "reason-react";
-      rev = "1fdc7b1b38c7aea6d412b28e7902f8cb338f565a";
-      hash = "sha256-lpYujcmNNrJKCDkrZwdGQBh6wWXLc3CKh/VbL2eYFHA=";
+      rev = "3ab8747623e43b259bf4db8375fa35a5c5265db4";
+      hash = "sha256-5GyKXZ1C8fQnY4ekzJQNOhdRrRU4inQxZGkuEkN8Suo=";
     };
     propagatedBuildInputs = [ ppxlib ];
   };
diff --git a/ocaml/overlay-ocaml-packages.nix b/ocaml/overlay-ocaml-packages.nix
index b4f7b48eb..3352835d7 100644
--- a/ocaml/overlay-ocaml-packages.nix
+++ b/ocaml/overlay-ocaml-packages.nix
@@ -48,6 +48,17 @@ let
         };
       };
 
+      ocamlPackages_5_1 = ocaml-ng.ocamlPackages_5_1.overrideScope' (oself: osuper: {
+        ocaml = osuper.ocaml.overrideAttrs (_: {
+          src = super.fetchFromGitHub {
+            owner = "ocaml";
+            repo = "ocaml";
+            rev = "a7840563fe9fe972d1f34f72f58d46d9dd67fa16";
+            hash = "sha256-9uEZm0IZv+TDoLwmpFKzCjkucuYDBBSjquQx9CqfhK0=";
+          };
+        });
+      });
+
       ocamlPackages_jst = ocaml-ng.ocamlPackages_4_14.overrideScope' (oself: osuper: {
         ocaml = (callPackage
           (import "${nixpkgs}/pkgs/development/compilers/ocaml/generic.nix" {
diff --git a/ocaml/piaf/default.nix b/ocaml/piaf/default.nix
index 4ce2990fd..38d69d462 100644
--- a/ocaml/piaf/default.nix
+++ b/ocaml/piaf/default.nix
@@ -24,8 +24,8 @@ buildDunePackage {
   src = fetchFromGitHub {
     owner = "anmonteiro";
     repo = "piaf";
-    rev = "daf09111b026eaca09e51330be656cc1b49fd4e6";
-    hash = "sha256-NUpu4LCkqeHJq6io6he+6kupei8Y2G+57D+MKEEtc8w=";
+    rev = "5c9561ba81ba3d3883cf4959541f5e2675516f88";
+    hash = "sha256-B1qpQTuv8buCKdrtbFNkKmZY+XTzbXEj98Kpf5Ych6U=";
   };
 
   checkInputs = [ alcotest dune-site ];