diff --git a/Dockerfile b/Dockerfile
index b169044f1..485b08a2f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:lunar
+FROM ubuntu:lunar@sha256:5a828e28de105c3d7821c4442f0f5d1c52dc16acf4999d5f31a3bc0f03f06edd
 
 WORKDIR /build/
 ENV PYENV_ROOT="/root/.pyenv"
diff --git a/poetry.lock b/poetry.lock
index 6779ba2ab..7e68d3fbe 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -159,4 +159,4 @@ files = [
 [metadata]
 lock-version = "2.1"
 python-versions = "^3.10"
-content-hash = "01bd15d9eeccfe8637f28c3f5c49af7943c375946002f6e716a6e4761f9fc0c9"
+content-hash = "22decc233fe3bda9e7e720da9914f4af7c7333b9d857e818e5799452ea0d8d2d"
diff --git a/pyproject.toml b/pyproject.toml
index f1c87d56e..b9b8affca 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,8 +14,8 @@ readme = "pylarky/README.md"
 python = "^3.10"
 
 [tool.poetry.group.dev.dependencies]
-pytest = "^7.4.4"
-setuptools = "^74.1.2"
+pytest = "7.4.4"
+setuptools = "74.1.3"
 
 [build-system]
 requires = ["setuptools", "poetry-core>=1.0.0"]