diff --git a/.gitea/release.yaml b/.gitea/release.yaml
index 6907e14..962899a 100644
--- a/.gitea/release.yaml
+++ b/.gitea/release.yaml
@@ -1 +1 @@
-version_descriptor: setup.py
+version_descriptor: pyproject.toml
diff --git a/flake.lock b/flake.lock
index 08e416f..f01d5cb 100644
--- a/flake.lock
+++ b/flake.lock
@@ -34,10 +34,31 @@
         "type": "github"
       }
     },
+    "pyproject-nix": {
+      "inputs": {
+        "nixpkgs": [
+          "nixpkgs"
+        ]
+      },
+      "locked": {
+        "lastModified": 1764134915,
+        "narHash": "sha256-xaKvtPx6YAnA3HQVp5LwyYG1MaN4LLehpQI8xEdBvBY=",
+        "owner": "pyproject-nix",
+        "repo": "pyproject.nix",
+        "rev": "2c8df1383b32e5443c921f61224b198a2282a657",
+        "type": "github"
+      },
+      "original": {
+        "owner": "pyproject-nix",
+        "repo": "pyproject.nix",
+        "type": "github"
+      }
+    },
     "root": {
       "inputs": {
         "flake-utils": "flake-utils",
-        "nixpkgs": "nixpkgs"
+        "nixpkgs": "nixpkgs",
+        "pyproject-nix": "pyproject-nix"
       }
     },
     "systems": {
diff --git a/flake.nix b/flake.nix
index 6b53cca..723e2da 100644
--- a/flake.nix
+++ b/flake.nix
@@ -4,22 +4,23 @@
   inputs = {
     nixpkgs.url = "github:NixOS/nixpkgs/nixos-25.05";
     flake-utils.url = "github:numtide/flake-utils";
+
+    pyproject-nix = {
+      url = "github:pyproject-nix/pyproject.nix";
+      inputs.nixpkgs.follows = "nixpkgs";
+    };
   };
 
-  outputs = { self, nixpkgs, flake-utils, ... }:
+  outputs = { self, nixpkgs, flake-utils, pyproject-nix }:
     flake-utils.lib.eachDefaultSystem (system:
       let
         pkgs = import nixpkgs { inherit system; };
 
-        python = pkgs.python313.withPackages (ps: with ps; [
-          isort
-          flake8
-          semver
-          toml
-          requests
-          pyyaml
-          packaging
-        ]);
+        pythonProject = pyproject-nix.lib.project.loadPyproject {
+          projectRoot = ./.;
+        };
+
+        pythonInterpreter = pkgs.python313;
 
         pythonPackage = pkgs.python3Packages.buildPythonPackage {
           name = "release-action";
@@ -32,24 +33,18 @@
               pkgs.envsubst
               pkgs.just
               pkgs.gitea-actions-runner
-              python
+              (pythonInterpreter.withPackages
+                (pythonProject.renderers.withPackages {
+                  python = pythonInterpreter;
+                  extraPackages = ps: with ps; [ flake8 isort ];
+                }))
             ];
           };
 
-          packages.default = pkgs.writers.writePython3Bin
-            "release-action"
-            {
-              libraries = with pkgs.python3Packages; [
-                semver # TODO move to setup.py?
-                toml
-                requests
-                pythonPackage
-                pyyaml
-                packaging
-              ];
-            }
-            (builtins.readFile ./src/main.py)
-          ;
+          packages.default = pythonInterpreter.pkgs.buildPythonPackage (
+            pythonProject.renderers.buildPythonPackage {
+              python = pythonInterpreter;
+            });
         }
     );
 }
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..d3df7ab
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,16 @@
+[project]
+name = "gitea-release-action"
+version = "0.0.1"
+description = "reusable action for release workflows"
+authors = [ ]
+requires-python = ">=3.13"
+dependencies = [
+  "semver",
+  "toml",
+  "requests",
+  "pyyaml",
+  "packaging"
+]
+
+[project.scripts]
+gitea-release-action = "main:main_cli"
diff --git a/setup.py b/setup.py
deleted file mode 100644
index 5ab564c..0000000
--- a/setup.py
+++ /dev/null
@@ -1,6 +0,0 @@
-from setuptools import setup
-
-setup(
-    name='release-action',
-    version='0.0.1',
-)
diff --git a/src/main.py b/src/main.py
index 94a9f02..6bd2e0b 100755
--- a/src/main.py
+++ b/src/main.py
@@ -248,7 +248,7 @@ def sync_versions(project_description: ProjectDescription):
             sync(artefact.version_descriptor)
 
 
-if __name__ == '__main__':
+def main_cli():
     parser = ArgumentParser()
     parser.add_argument('action', choices=[
         'declare',