diff --git a/shell.nix b/shell.nix
index 159cd42..d920a6f 100644
--- a/shell.nix
+++ b/shell.nix
@@ -27,6 +27,7 @@ in
   nativeBuildInputs = old.nativeBuildInputs ++ [
 
     pkgs.treefmt
+    pkgs.llvmPackages.clang # clang-format
     pkgs.nixpkgs-fmt
 
     (pkgs.python3.withPackages (ps: [
diff --git a/treefmt.toml b/treefmt.toml
index 8309d20..aacc3bb 100644
--- a/treefmt.toml
+++ b/treefmt.toml
@@ -1,3 +1,8 @@
+[formatter."c++"]
+command = "clang-format"
+options = [ "-i", "-style", "{BasedOnStyle: llvm, IndentWidth: 4, SortIncludes: false}" ]
+includes = [ "*.c", "*.cpp", "*.cc", "*.h", "*.hpp" ]
+
 [formatter.nix]
 command = "nixpkgs-fmt"
 includes = ["*.nix"]