diff --git a/README.md b/README.md
index 3ead1501..f655808e 100644
--- a/README.md
+++ b/README.md
@@ -246,14 +246,17 @@ use nix
 - [clang-format](https://clang.llvm.org/docs/ClangFormat.html).\
   You may restrict which languages should be formatted by `clang-format` using
   `clang-format.types_or`. For example to check only C and C++ files:
+
   ```nix
   clang-format = {
     enable = true;
     types_or = lib.mkForce [ "c" "c++" ];
   };
   ```
+
   Otherwise, the default internal list is used which includes everything that
   clang-format supports.
+
 - [clang-tidy](https://clang.llvm.org/extra/clang-tidy/)
 - [cmake-format](https://cmake-format.readthedocs.io/en/latest/)
 
@@ -380,6 +383,7 @@ use nix
 - [mdformat](https://github.com/hukkin/mdformat)
 - [mdl](https://github.com/markdownlint/markdownlint/)
 - [mdsh](https://zimbatm.github.io/mdsh/)
+- [rumdl](https://github.com/rvben/rumdl)
 
 ### Nix
 
diff --git a/flake.lock b/flake.lock
index c6c5cae8..c0ad03dc 100644
--- a/flake.lock
+++ b/flake.lock
@@ -38,11 +38,11 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1759417375,
-        "narHash": "sha256-O7eHcgkQXJNygY6AypkF9tFhsoDQjpNEojw3eFs73Ow=",
+        "lastModified": 1764947035,
+        "narHash": "sha256-EYHSjVM4Ox4lvCXUMiKKs2vETUSL5mx+J2FfutM7T9w=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "dc704e6102e76aad573f63b74c742cd96f8f1e6c",
+        "rev": "a672be65651c80d3f592a89b3945466584a22069",
         "type": "github"
       },
       "original": {