diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 45f6f6fcf..05cd52026 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -17,7 +17,7 @@
   sha: v1.3.4
   hooks:
     - id: reorder-python-imports
-      language_version: 'python3.9'
+      language_version: 'python3.7'
       args:
          - --py3-plus
 -   repo: https://github.com/asottile/pyupgrade
diff --git a/Dockerfile b/Dockerfile
index a4fc34a92..f2ec3812f 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,13 +1,13 @@
 ARG DOCKER_VERSION=19.03
-ARG PYTHON_VERSION=3.9.0
+ARG PYTHON_VERSION=3.7.9
 
 ARG BUILD_ALPINE_VERSION=3.12
 ARG BUILD_CENTOS_VERSION=7
-ARG BUILD_DEBIAN_VERSION=slim-buster
+ARG BUILD_DEBIAN_VERSION=slim-stretch
 
 ARG RUNTIME_ALPINE_VERSION=3.12
 ARG RUNTIME_CENTOS_VERSION=7
-ARG RUNTIME_DEBIAN_VERSION=buster-slim
+ARG RUNTIME_DEBIAN_VERSION=stretch-slim
 
 ARG DISTRO=alpine
 
@@ -38,7 +38,7 @@ RUN apt-get update && apt-get install --no-install-recommends -y \
     git \
     libc-dev \
     libffi-dev \
-    libgcc-8-dev \
+    libgcc-6-dev \
     libssl-dev \
     make \
     openssl \
@@ -68,8 +68,8 @@ WORKDIR /code/
 COPY docker-compose-entrypoint.sh /usr/local/bin/
 COPY --from=docker-cli /usr/local/bin/docker /usr/local/bin/docker
 RUN pip install \
-    virtualenv==20.2.2 \
-    tox==3.20.1
+    virtualenv==20.4.0 \
+    tox==3.21.2
 COPY requirements-dev.txt .
 COPY requirements-indirect.txt .
 COPY requirements.txt .
@@ -79,7 +79,7 @@ COPY tox.ini .
 COPY setup.py .
 COPY README.md .
 COPY compose compose/
-RUN tox --notest
+RUN tox -e py37 --notest
 COPY . .
 ARG GIT_COMMIT=unknown
 ENV DOCKER_COMPOSE_GITSHA=$GIT_COMMIT
diff --git a/Jenkinsfile b/Jenkinsfile
index 40629216a..c0f04dfa7 100644
--- a/Jenkinsfile
+++ b/Jenkinsfile
@@ -2,7 +2,7 @@
 
 def dockerVersions = ['19.03.13']
 def baseImages = ['alpine', 'debian']
-def pythonVersions = ['py39']
+def pythonVersions = ['py37']
 
 pipeline {
     agent none
diff --git a/Release.Jenkinsfile b/Release.Jenkinsfile
index 38cc53433..33f2f6487 100644
--- a/Release.Jenkinsfile
+++ b/Release.Jenkinsfile
@@ -2,7 +2,7 @@
 
 def dockerVersions = ['19.03.13', '18.09.9']
 def baseImages = ['alpine', 'debian']
-def pythonVersions = ['py39']
+def pythonVersions = ['py37']
 
 pipeline {
     agent none
diff --git a/requirements-indirect.txt b/requirements-indirect.txt
index 218a4eddd..b691f235b 100644
--- a/requirements-indirect.txt
+++ b/requirements-indirect.txt
@@ -23,6 +23,6 @@ pyrsistent==0.16.0
 smmap==3.0.4
 smmap2==3.0.1
 toml==0.10.1
-tox==3.20.1
-virtualenv==20.2.2
+tox==3.21.2
+virtualenv==20.4.0
 wcwidth==0.2.5
diff --git a/script/build/linux-entrypoint b/script/build/linux-entrypoint
index a0e86ee26..74f47620e 100755
--- a/script/build/linux-entrypoint
+++ b/script/build/linux-entrypoint
@@ -3,7 +3,7 @@
 set -ex
 
 CODE_PATH=/code
-VENV="${CODE_PATH}"/.tox/py39
+VENV="${CODE_PATH}"/.tox/py37
 
 cd "${CODE_PATH}"
 mkdir -p dist
diff --git a/script/test/all b/script/test/all
index ee5ef333f..dc6d7bacd 100755
--- a/script/test/all
+++ b/script/test/all
@@ -11,7 +11,7 @@ docker run --rm \
   "$TAG" tox -e pre-commit
 
 get_versions="docker run --rm
-    --entrypoint=/code/.tox/py39/bin/python
+    --entrypoint=/code/.tox/py37/bin/python
     $TAG
     /code/script/test/versions.py docker/docker-ce,moby/moby"
 
@@ -22,7 +22,7 @@ elif [ "$DOCKER_VERSIONS" == "all" ]; then
 fi
 
 BUILD_NUMBER=${BUILD_NUMBER-$USER}
-PY_TEST_VERSIONS=${PY_TEST_VERSIONS:-py39}
+PY_TEST_VERSIONS=${PY_TEST_VERSIONS:-py37}
 
 for version in $DOCKER_VERSIONS; do
   >&2 echo "Running tests against Docker $version"
diff --git a/tox.ini b/tox.ini
index 174fd5ccd..80b6e256d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,5 +1,5 @@
 [tox]
-envlist = py39,pre-commit
+envlist = py37,py39,pre-commit
 
 [testenv]
 usedevelop=True