diff --git a/flake.lock b/flake.lock
index 899a68d26d2ea..591caa440d793 100644
--- a/flake.lock
+++ b/flake.lock
@@ -48,11 +48,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1748399823,
-        "narHash": "sha256-kahD8D5hOXOsGbNdoLLnqCL887cjHkx98Izc37nDjlA=",
+        "lastModified": 1766198367,
+        "narHash": "sha256-f1L1rCEu2Zew6zdiZ38jJDZd65ktE7UN+Gqn2LHPiFI=",
         "owner": "oxalica",
         "repo": "rust-overlay",
-        "rev": "d68a69dc71bc19beb3479800392112c2f6218159",
+        "rev": "66bb33fdfb50b1ee724381c3f5d6012dac6c89b3",
         "type": "github"
       },
       "original": {
diff --git a/rust-toolchain b/rust-toolchain
index b2584b239291d..b26ab2ac7f8b2 100644
--- a/rust-toolchain
+++ b/rust-toolchain
@@ -9,6 +9,7 @@
 #   * NOTE: You may have to change this ocaml file in a follow up commit as ocamlrep
 #     has a dependency on buck2 git trunk.
 # * Update `../monarch/rust-toolchain` (one instance)
+# * Update flake.lock via `nix flake update rust-overlay`
 
 # @rustc_version: rustc 1.91.0-nightly (02c7b1a7a 2025-09-13)
 channel = "nightly-2025-09-14"