diff --git a/changelog.d/5-internal/WPB-28448-add-headroom-to-treefmt_-pin-to-0_5_0_0-_github-master_ b/changelog.d/5-internal/WPB-28448-add-headroom-to-treefmt_-pin-to-0_5_0_0-_github-master_
new file mode 100644
index 00000000000..022fa05f4f6
--- /dev/null
+++ b/changelog.d/5-internal/WPB-28448-add-headroom-to-treefmt_-pin-to-0_5_0_0-_github-master_
@@ -0,0 +1 @@
+Add headroom to treefmt, pin to 0.5.0.0 (github master).
diff --git a/flake.lock b/flake.lock
index 67d13b227d8..38e18bceec0 100644
--- a/flake.lock
+++ b/flake.lock
@@ -249,6 +249,23 @@
         "type": "github"
       }
     },
+    "headroom": {
+      "flake": false,
+      "locked": {
+        "lastModified": 1788175700,
+        "narHash": "sha256-7Pj8dP56vbFzx6SnjFpA2vRY/hDCNvx6yIyc2A2B7NU=",
+        "owner": "xwinus",
+        "repo": "headroom",
+        "rev": "010ed0ca68f0af9026bb613800cbeae80be6ebbd",
+        "type": "github"
+      },
+      "original": {
+        "owner": "xwinus",
+        "repo": "headroom",
+        "rev": "010ed0ca68f0af9026bb613800cbeae80be6ebbd",
+        "type": "github"
+      }
+    },
     "hsaml2": {
       "flake": false,
       "locked": {
@@ -392,6 +409,7 @@
         "flake-utils": "flake-utils",
         "hasql-migration": "hasql-migration",
         "hasql-resource-pool": "hasql-resource-pool",
+        "headroom": "headroom",
         "hsaml2": "hsaml2",
         "hspec-wai": "hspec-wai",
         "http-client": "http-client",
diff --git a/flake.nix b/flake.nix
index 46255be3e45..7e5b5c6ab99 100644
--- a/flake.nix
+++ b/flake.nix
@@ -114,6 +114,13 @@
       url = "github:velveteer/arbiter?rev=b9c57eb1f8277d97616aa449bea471fe9ce14eda";
       flake = false;
     };
+
+    headroom = {
+      # https://github.com/xwinus/headroom/issues/117
+      # this pin should be removed once 0.5.0.0 has been released.
+      url = "github:xwinus/headroom?rev=010ed0ca68f0af9026bb613800cbeae80be6ebbd";
+      flake = false;
+    };
   };
 
   outputs = inputs@{ nixpkgs, nixpkgs_24_11, flake-utils, tom-bombadil, sbomnix, ... }:
diff --git a/nix/haskell-pins.nix b/nix/haskell-pins.nix
index 13ebf988279..05531592ddf 100644
--- a/nix/haskell-pins.nix
+++ b/nix/haskell-pins.nix
@@ -71,6 +71,10 @@ let
       };
     };
 
+    headroom = {
+      src = inputs.headroom;
+    };
+
     bloodhound = {
       src = inputs.bloodhound;
     };
@@ -149,7 +153,7 @@ let
     # N.B. only the listed packages work. If you want to use another:
     # - list it here
     # - patch it on the fork (if required)
-    # 
+    #
     # Can't currently be removed because amazonka-dynamodb-attributevalue
     # does not exist on hackage
     amazonka = {
diff --git a/nix/wire-server.nix b/nix/wire-server.nix
index c3a3010efe6..13495ea2be2 100644
--- a/nix/wire-server.nix
+++ b/nix/wire-server.nix
@@ -470,7 +470,7 @@ let
     pkgs.cfssl
     pkgs.awscli2
     (hlib.justStaticExecutables pkgs.haskellPackages.cabal-fmt)
-    (hlib.justStaticExecutables pkgs.haskellPackages.headroom)
+    (hlib.justStaticExecutables (hlib.dontCheck haskellPackages.headroom))
     (hlib.justStaticExecutables pkgs.haskellPackages.weeder)
   ] ++ pkgs.lib.optionals pkgs.stdenv.isLinux [
     pkgs.skopeo
diff --git a/treefmt.toml b/treefmt.toml
index cc49a82bf60..516cbd86fbb 100644
--- a/treefmt.toml
+++ b/treefmt.toml
@@ -10,6 +10,13 @@ excludes = [
   "dist-newstyle/"
 ]
 
+[formatter.headroom]
+command = "hack/bin/headroom-treefmt.sh"
+includes = ["*.hs", "*.hsc", "*.rs"]
+excludes = [
+  "dist-newstyle/",
+  "services/wire-server-enterprise/*",
+]
 
 [formatter.shellcheck]
 command = "shellcheck"