diff --git a/.github/workflows/workflow.yml b/.github/workflows/workflow.yml
index 9784aa1..97a40d6 100644
--- a/.github/workflows/workflow.yml
+++ b/.github/workflows/workflow.yml
@@ -15,7 +15,7 @@ jobs:
   example:
     runs-on: ubuntu-latest
     container:
-      image: semnil/tfdiagrams:0.3.0
+      image: semnil/tfdiagrams:0.3.1
 
     steps:
       - uses: actions/create-github-app-token@v1
diff --git a/Dockerfile b/Dockerfile
index e7c11b8..2a3618e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,15 +10,6 @@ RUN apk update && apk add \
   python3-dev \
   py3-pip
 
-WORKDIR /app
-COPY tfdiagrams/ ./tfdiagrams/
-COPY poetry.lock .
-COPY pyproject.toml .
-
-RUN pip3 install poetry --break-system-packages \
-  && pip3 install packaging==24.1 --break-system-packages \
-  && poetry config virtualenvs.create false --local
-
-RUN /usr/bin/poetry install
+RUN pip3 install tfdiagrams==0.3.0 --break-system-packages
 
 ENTRYPOINT []
diff --git a/pyproject.toml b/pyproject.toml
index ce1dba7..86b0785 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "tfdiagrams"
-version = "0.3.0"
+version = "0.3.1"
 description = ""
 authors = ["Tetsuya Shinone <info@semnil.com>"]