diff --git a/.github/workflows/opam-ci.yml b/.github/workflows/opam-ci.yml
index 658cf1f90..7fa2ca094 100644
--- a/.github/workflows/opam-ci.yml
+++ b/.github/workflows/opam-ci.yml
@@ -22,9 +22,9 @@ jobs:
           - {ocaml-compiler: '4.13.x', os: ubuntu-latest}
           - {ocaml-compiler: '4.14.x', os: ubuntu-latest}
           - {ocaml-compiler: 'ocaml-base-compiler.5.3.0', os: ubuntu-latest}
-          - {ocaml-compiler: 'ocaml-base-compiler.5.4.0~alpha1', os: ubuntu-latest}
-          - {ocaml-compiler: 'ocaml-base-compiler.5.4.0~alpha1', os: macos-13}
-          - {ocaml-compiler: 'ocaml-base-compiler.5.4.0~alpha1', os: macos-14}
+          - {ocaml-compiler: 'ocaml-base-compiler.5.4.0~beta2', os: ubuntu-latest}
+          - {ocaml-compiler: 'ocaml-base-compiler.5.4.0~beta2', os: macos-13}
+          - {ocaml-compiler: 'ocaml-base-compiler.5.4.0~beta2', os: macos-14}
             # looks like setup-ocaml@v3 can only run actions on windows for
             # OCaml >= 4.13
             # https://github.com/ocaml/setup-ocaml/issues/822#issuecomment-2215525942
diff --git a/flake.lock b/flake.lock
index 4fbf825e5..d45d1cdf3 100644
--- a/flake.lock
+++ b/flake.lock
@@ -5,11 +5,11 @@
         "nixpkgs": "nixpkgs_2"
       },
       "locked": {
-        "lastModified": 1754239449,
-        "narHash": "sha256-MuBdH0pXcN0wVb57Y92ppAd2mQ/z6pJj+jxBjMUQ84g=",
+        "lastModified": 1757832179,
+        "narHash": "sha256-Uxp1M2PiYxP2XbnggrrA1sKt5jT90ppZpLGsMma/DMo=",
         "owner": "nix-ocaml",
         "repo": "nix-overlays",
-        "rev": "123166a438d3e9e2d0d0666ed88bfe6fdb08b2a0",
+        "rev": "cee7f41d71c0642f517c75dc87c4c379d5a10f52",
         "type": "github"
       },
       "original": {
@@ -20,17 +20,17 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1754196730,
-        "narHash": "sha256-qwbI79PEvEHdThZh4XMDuzo2de5XyQACr890uMOZQD8=",
+        "lastModified": 1757752761,
+        "narHash": "sha256-HBM2YTKSegLZjdamfqH9KADj2zQBQBNQHmwdrYkatpg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "b16813baa89e3bf87c62d459e6c8b2c3da57a369",
+        "rev": "4b46c744cbd5f9336027dff287e74ead84d80041",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "b16813baa89e3bf87c62d459e6c8b2c3da57a369",
+        "rev": "4b46c744cbd5f9336027dff287e74ead84d80041",
         "type": "github"
       }
     },