diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 4a66823..401fdf0 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -16,14 +16,8 @@ jobs:
         python-version: 3.8
     - name: Install dependencies
       run: |
-        python -m pip install --upgrade pip
-        pip install pipenv
-        pipenv install --dev --deploy
-    - name: Formatting
-      run: |
-        # check that the source files are formatted correctly
-        pipenv run yapf -q *.py
+        pip install poetry
+        poetry install
     - name: Linting
       run: |
-        pipenv run mypy *.py
-        pipenv run pylint *.py
+        make lint
diff --git a/.gitignore b/.gitignore
index d7f7a42..06017d7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,2 @@
 .mypy_cache
+poetry.lock
diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..ee5f83c
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,23 @@
+
+# https://tech.davis-hansson.com/p/make/
+SHELL := bash
+.ONESHELL:
+.SILENT:
+.SHELLFLAGS := -eux -o pipefail -c
+.DELETE_ON_ERROR:
+.DEFAULT_GOAL := all
+MAKEFLAGS += --warn-undefined-variables
+MAKEFLAGS += --no-builtin-rules
+
+.PHONY: all
+all: lint ## Run lint and test (default goal)
+
+.PHONY: lint
+lint: ## Lint all source code
+	poetry run yapf -q *.py
+	poetry run pylint *.py
+	poetry run mypy *.py
+
+.PHONY: help
+help: ## Print this help text
+	@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-15s\033[0m %s\n", $$1, $$2}'
diff --git a/Pipfile b/Pipfile
deleted file mode 100644
index c5723dc..0000000
--- a/Pipfile
+++ /dev/null
@@ -1,15 +0,0 @@
-[[source]]
-url = 'https://pypi.python.org/simple'
-
-[requires]
-python_version = '3.8'
-
-[packages]
-pyyaml = '*'
-requests = '*'
-
-[dev-packages]
-rope = '==0.17.0'
-pylint = '==2.5.3'
-yapf = '==0.30.0'
-mypy = '== 0.782'
diff --git a/pyproject.toml b/pyproject.toml
new file mode 100644
index 0000000..f5f9cd5
--- /dev/null
+++ b/pyproject.toml
@@ -0,0 +1,22 @@
+[build-system]
+requires = ["poetry>=1.0"]
+build-backend = "poetry.masonry.api"
+
+[tool.poetry]
+name = "kube-stale-resources"
+version = "1.0.0"
+description = "Utility augmenting 'kubectl diff' to detect stale resources in Kubernetes clusters between local YAML manifests (target state) and the cluster (live state)."
+authors = ["Christian Nicolai"]
+license = "Apache-2.0"
+homepage = "https://dev.mycrobase.de/gitea/cn/kube-stale-resources"
+
+[tool.poetry.dependencies]
+python = "^3.8"
+pyyaml = "5.3.1"
+requests = "2.24.0"
+
+[tool.poetry.dev-dependencies]
+mypy = "0.782"
+pylint = "2.5.3"
+rope = "0.17.0"
+yapf = "0.30.0"