diff --git a/.circleci/config.yml b/.circleci/config.yml
index 073960d..36311de 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -11,7 +11,7 @@ executors:
         type: enum
         enum: ["3.10", "3.11", "3.12", "3.13", "3.14"]
     docker:
-      - image: "ghcr.io/astral-sh/uv:python<<parameters.version>>-bookworm"
+      - image: "ghcr.io/astral-sh/uv:python<<parameters.version>>-trixie"
     resource_class: small
     environment:
       FORCE_COLOR: "1"
@@ -145,6 +145,69 @@ jobs:
           files: "coverage-results/coverage-cpython<<parameters.python_version>>-<<parameters.event_loop>>.xml"
           flags: "cpython<<parameters.python_version>>,<<parameters.event_loop>>"
 
+  test-freethreaded:
+    executor:
+      name: cpython_executor
+      version: <<parameters.python_version>>
+    parameters:
+      python_version:
+        type: enum
+        description: "python version"
+        enum: ["3.13", "3.14"]
+      event_loop:
+        type: enum
+        description: "event loop type"
+        enum: ["asyncio", "uvloop"]
+    environment:
+      COVERAGE_FILE: "coverage-results/.coverage.cpython<<parameters.python_version>>t-<<parameters.event_loop>>"
+      HYPOTHESIS_PROFILE: "ci"
+      BIND_ADDR: "127.0.0.1"
+    steps:
+      - checkout
+      - attach_workspace:
+          at: dist
+      - run: uv python install <<parameters.python_version>>t
+      - run: uv venv --python=<<parameters.python_version>>t
+      - run: uv pip install --python=<<parameters.python_version>>t -r requirements-dev.txt
+      - when:
+          condition:
+            equal: ["uvloop", <<parameters.event_loop>>]
+          steps:
+            - run: uv pip install $(find dist -name aiosmtplib-*.whl)[uvloop]
+      - unless:
+          condition:
+            equal: ["uvloop", <<parameters.event_loop>>]
+          steps:
+            - run: uv pip install $(find dist -name aiosmtplib-*.whl)
+      - run: |
+          uv run --python=<<parameters.python_version>>t --with aiosmtplib --no-project -- python -m pytest \
+            --cov \
+            --cov-report=xml:coverage-results/coverage-cpython<<parameters.python_version>>t-<<parameters.event_loop>>.xml \
+            --cov-config=pyproject.toml \
+            --junitxml=test-results/junit-cpython<<parameters.python_version>>t-<<parameters.event_loop>>.xml \
+            --override-ini=pythonpath= \
+            --event-loop=<<parameters.event_loop>> \
+            --bind-addr=$BIND_ADDR \
+            --hypothesis-profile $HYPOTHESIS_PROFILE
+      - store_artifacts:
+          path: test-results
+      - store_test_results:
+          path: test-results
+      - persist_to_workspace:
+          root: coverage-results
+          paths:
+            - .coverage.*
+      - codecov/upload:
+          report_type: test_results
+          disable_search: true
+          files: "test-results/junit-cpython<<parameters.python_version>>t-<<parameters.event_loop>>.xml"
+          flags: "cpython<<parameters.python_version>>t,<<parameters.event_loop>>"
+      - codecov/upload:
+          report_type: coverage
+          disable_search: true
+          files: "coverage-results/coverage-cpython<<parameters.python_version>>t-<<parameters.event_loop>>.xml"
+          flags: "cpython<<parameters.python_version>>t,<<parameters.event_loop>>"
+
   test-pypy:
     executor:
       name: pypy_executor
@@ -246,6 +309,16 @@ workflows:
               python_version: ["3.10", "3.11", "3.12", "3.13", "3.14"]
           requires:
             - build
+      - test-freethreaded:
+          <<: *base-job
+          name: "test-asyncio-<< matrix.python_version >>t"
+          matrix:
+            alias: "test-freethreaded-asyncio"
+            parameters:
+              event_loop: ["asyncio"]
+              python_version: ["3.13", "3.14"]
+          requires:
+            - build
       - test:
           <<: *base-job
           name: "test-uvloop-<< matrix.python_version >>"
@@ -257,11 +330,23 @@ workflows:
           requires:
             - build
             - "test-asyncio-<< matrix.python_version >>"
+      - test-freethreaded:
+          <<: *base-job
+          name: "test-uvloop-<< matrix.python_version >>t"
+          matrix:
+            alias: "test-freethreaded-uvloop"
+            parameters:
+              event_loop: ["uvloop"]
+              python_version: ["3.13", "3.14"]
+          requires:
+            - build
       - coverage:
           <<: *base-job
           requires:
             - test-cpython-asyncio
             - test-cpython-uvloop
+            - test-freethreaded-asyncio
+            - test-freethreaded-uvloop
             - test-asyncio-pypy3.11
       - deploy:
           requires:
@@ -270,6 +355,8 @@ workflows:
             - docs
             - test-cpython-asyncio
             - test-cpython-uvloop
+            - test-freethreaded-asyncio
+            - test-freethreaded-uvloop
             - test-asyncio-pypy3.11
           context:
             - docker-hub-credentials
diff --git a/src/aiosmtplib/__init__.py b/src/aiosmtplib/__init__.py
index 1eb7c31..92e2e57 100644
--- a/src/aiosmtplib/__init__.py
+++ b/src/aiosmtplib/__init__.py
@@ -34,7 +34,7 @@
 
 
 __title__ = "aiosmtplib"
-__version__ = "5.0.0"
+__version__ = "5.0.1dev0"
 __author__ = "Cole Maclean"
 __license__ = "MIT"
 __copyright__ = "Copyright 2022 Cole Maclean"