diff --git a/.github/workflows/docs.yml b/.github/workflows/docs.yml
index ce613342..69bc72a7 100644
--- a/.github/workflows/docs.yml
+++ b/.github/workflows/docs.yml
@@ -14,7 +14,7 @@ jobs:
     - name: Setup Python
       uses: actions/setup-python@v1
       with:
-        python-version: '3.8'
+        python-version: '3.9'
         architecture: 'x64'
 
     - uses: actions/cache@v1
diff --git a/.github/workflows/publish.yml b/.github/workflows/publish.yml
index c6e638f3..aab2cff3 100644
--- a/.github/workflows/publish.yml
+++ b/.github/workflows/publish.yml
@@ -20,10 +20,10 @@ jobs:
           key: ${{ runner.os }}-pip-${{ hashFiles('**/poetry.lock') }}
           restore-keys: |
             ${{ runner.os }}-pip-
-      - name: Set up Python 3.8
+      - name: Set up Python 3.9
         uses: actions/setup-python@v1
         with:
-          python-version: 3.8
+          python-version: 3.9
       - name: Build publish
         run: |
           python -m pip install poetry poetry-dynamic-versioning
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index f643e2f7..cd4f8553 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -10,7 +10,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
         os: [ubuntu-latest, windows-latest, macos-latest]
 
     steps:
diff --git a/README.md b/README.md
index 956d3449..2d4c7d05 100644
--- a/README.md
+++ b/README.md
@@ -40,7 +40,7 @@ Options:
   --specify-tags           Use along with --generate-routers to generate specific routers from given list of tags.
   -c, --custom-visitors    PATH - A custom visitor that adds variables to the template.
   -d, --output-model-type  Specify a Pydantic base model to use (see [datamodel-code-generator](https://github.com/koxudaxi/datamodel-code-generator); default is `pydantic.BaseModel`).
-  -p, --python-version     Specify a Python version to target (default is `3.8`).
+  -p, --python-version     Specify a Python version to target (default is `3.9`).
   --install-completion     Install completion for the current shell.
   --show-completion        Show completion for the current shell, to copy it
                            or customize the installation.
diff --git a/fastapi_code_generator/patches.py b/fastapi_code_generator/patches.py
index 9f5f6654..f3f4dd37 100644
--- a/fastapi_code_generator/patches.py
+++ b/fastapi_code_generator/patches.py
@@ -1,7 +1,11 @@
+# todo: remove this file when the following PR is merged into datamodels-code-generator:
+#
+# https://github.com/koxudaxi/datamodel-code-generator/pull/2379
+
 import logging
 from itertools import groupby
 from pathlib import Path
-from typing import NamedTuple
+from typing import NamedTuple, Optional, Union
 
 from datamodel_code_generator.format import CodeFormatter
 from datamodel_code_generator.imports import IMPORT_ANNOTATIONS, Import, Imports
@@ -31,17 +35,17 @@ def __alias_shadowed_imports(
 
     def _parse(  # noqa: PLR0912, PLR0914, PLR0915
         self: base.Parser,
-        with_import: bool | None = True,  # noqa: FBT001, FBT002
-        format_: bool | None = True,  # noqa: FBT001, FBT002
-        settings_path: Path | None = None,
-    ) -> str | dict[tuple[str, ...], base.Result]:
+        with_import: Optional[bool] = True,  # noqa: FBT001, FBT002
+        format_: Optional[bool] = True,  # noqa: FBT001, FBT002
+        settings_path: Optional[Path] = None,
+    ) -> Union[str, dict[tuple[str, ...], base.Result]]:
         self.parse_raw()
 
         if with_import:
             self.imports.append(IMPORT_ANNOTATIONS)
 
         if format_:
-            code_formatter: CodeFormatter | None = CodeFormatter(
+            code_formatter: Optional[CodeFormatter] = CodeFormatter(
                 self.target_python_version,
                 settings_path,
                 self.wrap_string_literal,
diff --git a/poetry.lock b/poetry.lock
index 58b960fe..e8b87169 100644
--- a/poetry.lock
+++ b/poetry.lock
@@ -652,10 +652,7 @@ files = [
 [package.dependencies]
 annotated-types = ">=0.4.0"
 pydantic-core = "2.20.1"
-typing-extensions = [
-    {version = ">=4.12.2", markers = "python_version >= \"3.13\""},
-    {version = ">=4.6.1", markers = "python_version < \"3.13\""},
-]
+typing-extensions = {version = ">=4.6.1", markers = "python_version < \"3.13\""}
 
 [package.extras]
 email = ["email-validator (>=2.0.0)"]
@@ -1120,5 +1117,5 @@ files = [
 
 [metadata]
 lock-version = "2.1"
-python-versions = "^3.9.0"
-content-hash = "d312fae363b433a0f2497be586a9db4f3a53a5f81cbf5969f0a8d51c1d9cab48"
+python-versions = ">=3.9,<3.13"
+content-hash = "4c877a8538b055a678c7b0389bbe91cb862a0ecbc41d8fbd843b43be7999b23d"
diff --git a/pyproject.toml b/pyproject.toml
index d567f743..d3726ecc 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,7 +13,6 @@ classifiers = [
         "Natural Language :: English",
         "License :: OSI Approved :: MIT License",
         "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.8",
         "Programming Language :: Python :: 3.9",
         "Programming Language :: Python :: 3.10",
         "Programming Language :: Python :: 3.11",
@@ -30,7 +29,7 @@ pattern = "^(?P<base>\\d+\\.\\d+\\.\\d+)(-?((?P<stage>[a-zA-Z]+)\\.?(?P<revision
 fastapi-codegen = "fastapi_code_generator.__main__:app"
 
 [tool.poetry.dependencies]
-python = "^3.9.0"
+python = ">=3.9,<3.13"
 typer = {extras = ["all"], version = ">=0.2.1,<0.13.0"}
 datamodel-code-generator =  {extras = ["http"], version = "0.28.5"}
 stringcase = "^1.2.0"
@@ -45,7 +44,7 @@ typed-ast = [
 #mkdocs = {version = "1.1.2", optional = true}
 #mkdocs-material = {version = "5.2.3", optional = true}
 
-[tool.poetry.dev-dependencies]
+[tool.poetry.group.dev.dependencies]
 pytest = "^8.2"
 pytest-cov = "*"
 pytest-mock = "*"
@@ -61,7 +60,7 @@ isort = "==5.13.2"
 [tool.black]
 line-length = 88
 skip-string-normalization = true
-target-version = ['py38']
+target-version = ['py39']
 exclude = '(tests/data|\.eggs|\.git|\.hg|\.mypy_cache|\.nox|\.tox|\.venv|_build|buck-out|build|dist|.*\/models\.py.*|.*\/models\/.*)'
 
 [tool.isort]