diff --git a/.circleci/config.yml b/.circleci/config.yml
index 248cd9855c..e6694648f9 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -26,13 +26,13 @@ commands:
 jobs:
   test:
     docker:
-      - image: circleci/python:3.7.2-stretch
+      - image: circleci/python:3.6
     steps:
       - checkout
       - setup_remote_docker
       - install-go
       - run: go get -u -v golang.org/x/lint/golint
-      - run: sudo pip3 install black
+      - run: sudo pip install black
       - run:
           name: Lint
           command: make lint
@@ -44,7 +44,7 @@ jobs:
           command: make test-python
   test-release:
     docker:
-      - image: circleci/python:3.7.2-stretch
+      - image: circleci/python:3.6
     steps:
       - checkout
       - run:
@@ -52,7 +52,7 @@ jobs:
           command: make find-missing-version
   build-and-deploy:
     docker:
-      - image: circleci/python:3.7.2-stretch
+      - image: circleci/python:3.6
     steps:
       - checkout
       - setup_remote_docker
@@ -60,7 +60,7 @@ jobs:
       - run: make ci-build-images
       - run: make ci-build-cli
       - return-if-not-deployed-branch
-      - run: sudo pip3 install awscli
+      - run: sudo pip install awscli
       - run: make ci-push-images
       - run: make ci-build-and-upload-cli
 
diff --git a/build/find-missing-version.sh b/build/find-missing-version.sh
index f87d893f94..87ece3f518 100755
--- a/build/find-missing-version.sh
+++ b/build/find-missing-version.sh
@@ -23,7 +23,7 @@ output=$(cd "$ROOT" && find . -type f \
 ! -path "./build/find-missing-version.sh" \
 ! -path "./.git/*" \
 ! -name ".*" \
--exec grep -R -A 50 -e "CORTEX_VERSION" {} \+)
+-exec grep -R -A 50 -e "CORTEX_VERSION" {} \;)
 
 output=$(echo "$output" | grep -e "master")
 
diff --git a/build/lint.sh b/build/lint.sh
index 7477dcb9a1..a70bd6b571 100755
--- a/build/lint.sh
+++ b/build/lint.sh
@@ -70,7 +70,7 @@ output=$(cd "$ROOT" && find . -type f \
 ! -name "*.md" \
 ! -name ".*" \
 ! -name "Dockerfile" \
--exec grep -L "Copyright 2019 Cortex Labs, Inc" {} \+)
+-exec grep -L "Copyright 2019 Cortex Labs, Inc" {} \;)
 if [[ $output ]]; then
   echo "File(s) are missing Cortex license:"
   echo "$output"
diff --git a/images/downloader/Dockerfile b/images/downloader/Dockerfile
index 0c87a1f6f4..149ac2d602 100644
--- a/images/downloader/Dockerfile
+++ b/images/downloader/Dockerfile
@@ -3,21 +3,20 @@ FROM ubuntu:18.04
 ENV PYTHONPATH="/src:${PYTHONPATH}"
 
 RUN apt-get update -qq && apt-get install -y -q \
-        python3 \
-        python3-dev \
-        python3-pip \
+        curl \
+        python3.6 \
+        python3.6-distutils \
     && apt-get clean -qq && rm -rf /var/lib/apt/lists/* && \
-    pip3 install --upgrade \
-        pip \
-        setuptools \
-    && rm -rf /root/.cache/pip*
+    curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
+    python3.6 get-pip.py && \
+    rm -rf /root/.cache/pip*
 
 COPY pkg/workloads/cortex/lib/requirements.txt /src/cortex/lib/requirements.txt
-RUN pip3 install -r /src/cortex/lib/requirements.txt && \
+RUN pip install -r /src/cortex/lib/requirements.txt && \
     rm -rf /root/.cache/pip*
 
 COPY pkg/workloads/cortex/consts.py /src/cortex/
 COPY pkg/workloads/cortex/lib /src/cortex/lib
 COPY pkg/workloads/cortex/downloader /src/cortex/downloader
 
-ENTRYPOINT ["/usr/bin/python3", "/src/cortex/downloader/download.py"]
+ENTRYPOINT ["/usr/bin/python3.6", "/src/cortex/downloader/download.py"]
diff --git a/images/manager/Dockerfile b/images/manager/Dockerfile
index c2b6babd02..07ba14c6fe 100644
--- a/images/manager/Dockerfile
+++ b/images/manager/Dockerfile
@@ -1,10 +1,10 @@
-FROM python:3.7-alpine3.10
+FROM python:3.6-alpine3.10
 
 WORKDIR /root
 
 ENV PATH /root/.local/bin:$PATH
 
-RUN pip3 install awscli --upgrade --user && \
+RUN pip install awscli --upgrade --user && \
     rm -rf /root/.cache/pip*
 
 RUN apk add --no-cache bash curl gettext jq openssl
diff --git a/images/onnx-serve-gpu/Dockerfile b/images/onnx-serve-gpu/Dockerfile
index 792d2d0533..5a076e340f 100644
--- a/images/onnx-serve-gpu/Dockerfile
+++ b/images/onnx-serve-gpu/Dockerfile
@@ -2,16 +2,6 @@ FROM nvidia/cuda:10.1-cudnn7-devel
 
 ARG ONNXRUNTIME_VERSION="0.5.0"
 
-RUN apt-get update -qq && apt-get install -y -q \
-        python3 \
-        python3-dev \
-        python3-pip \
-    && apt-get clean -qq && rm -rf /var/lib/apt/lists/* && \
-    pip3 install --upgrade \
-        pip \
-        setuptools \
-    && rm -rf /root/.cache/pip*
-
 RUN apt-get update -qq && apt-get install -y -q \
         build-essential \
         curl \
@@ -23,16 +13,20 @@ RUN apt-get update -qq && apt-get install -y -q \
         software-properties-common \
         unzip \
         zlib1g-dev \
-    && apt-get clean -qq && rm -rf /var/lib/apt/lists/*
-
+        python3.6-dev \
+        python3.6-distutils \
+    && apt-get clean -qq && rm -rf /var/lib/apt/lists/* && \
+    curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
+    python3.6 get-pip.py && \
+    rm -rf /root/.cache/pip*
 
 ENV PYTHONPATH "${PYTHONPATH}:/src:/mnt/project"
 
 COPY pkg/workloads/cortex/lib/requirements.txt /src/cortex/lib/requirements.txt
 COPY pkg/workloads/cortex/onnx_serve/requirements.txt /src/cortex/onnx_serve/requirements.txt
-RUN pip3 install -r /src/cortex/lib/requirements.txt && \
-    pip3 install -r /src/cortex/onnx_serve/requirements.txt && \
-    pip3 install onnxruntime-gpu==${ONNXRUNTIME_VERSION} && \
+RUN pip install -r /src/cortex/lib/requirements.txt && \
+    pip install -r /src/cortex/onnx_serve/requirements.txt && \
+    pip install onnxruntime-gpu==${ONNXRUNTIME_VERSION} && \
     rm -rf /root/.cache/pip*
 
 COPY pkg/workloads/cortex/consts.py /src/cortex
diff --git a/images/onnx-serve/Dockerfile b/images/onnx-serve/Dockerfile
index 0f238af080..f0e367e85d 100644
--- a/images/onnx-serve/Dockerfile
+++ b/images/onnx-serve/Dockerfile
@@ -2,16 +2,6 @@ FROM ubuntu:18.04
 
 ARG ONNXRUNTIME_VERSION="0.5.0"
 
-RUN apt-get update -qq && apt-get install -y -q \
-        python3 \
-        python3-dev \
-        python3-pip \
-    && apt-get clean -qq && rm -rf /var/lib/apt/lists/* && \
-    pip3 install --upgrade \
-        pip \
-        setuptools \
-    && rm -rf /root/.cache/pip*
-
 RUN apt-get update -qq && apt-get install -y -q \
         build-essential \
         curl \
@@ -23,16 +13,20 @@ RUN apt-get update -qq && apt-get install -y -q \
         software-properties-common \
         unzip \
         zlib1g-dev \
-    && apt-get clean -qq && rm -rf /var/lib/apt/lists/*
-
+        python3.6-dev \
+        python3.6-distutils \
+    && apt-get clean -qq && rm -rf /var/lib/apt/lists/* && \
+    curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py && \
+    python3.6 get-pip.py && \
+    rm -rf /root/.cache/pip*
 
 ENV PYTHONPATH "${PYTHONPATH}:/src:/mnt/project"
 
 COPY pkg/workloads/cortex/lib/requirements.txt /src/cortex/lib/requirements.txt
 COPY pkg/workloads/cortex/onnx_serve/requirements.txt /src/cortex/onnx_serve/requirements.txt
-RUN pip3 install -r /src/cortex/lib/requirements.txt && \
-    pip3 install -r /src/cortex/onnx_serve/requirements.txt && \
-    pip3 install onnxruntime==${ONNXRUNTIME_VERSION} && \
+RUN pip install -r /src/cortex/lib/requirements.txt && \
+    pip install -r /src/cortex/onnx_serve/requirements.txt && \
+    pip install onnxruntime==${ONNXRUNTIME_VERSION} && \
     rm -rf /root/.cache/pip*
 
 COPY pkg/workloads/cortex/consts.py /src/cortex
diff --git a/images/test/Dockerfile b/images/test/Dockerfile
index 4ccca4e6af..07c63a0d57 100644
--- a/images/test/Dockerfile
+++ b/images/test/Dockerfile
@@ -1,10 +1,10 @@
-FROM python:3.7
+FROM python:3.6
 
 ENV PYTHONPATH="/src:${PYTHONPATH}"
 
 COPY pkg/workloads/cortex/lib/requirements.txt /src/cortex/lib/requirements.txt
-RUN pip3 install -r /src/cortex/lib/requirements.txt && \
-    pip3 install pytest mock && \
+RUN pip install -r /src/cortex/lib/requirements.txt && \
+    pip install pytest mock && \
     rm -rf /root/.cache/pip*
 
 COPY pkg/workloads /src
diff --git a/images/tf-api/Dockerfile b/images/tf-api/Dockerfile
index c0c7843b24..c64f05a8ce 100644
--- a/images/tf-api/Dockerfile
+++ b/images/tf-api/Dockerfile
@@ -17,8 +17,8 @@ RUN apt-get update -qq && apt-get install -y -q \
 
 COPY pkg/workloads/cortex/lib/requirements.txt /src/cortex/lib/requirements.txt
 COPY pkg/workloads/cortex/tf_api/requirements.txt /src/cortex/tf_api/requirements.txt
-RUN pip3 install -r /src/cortex/lib/requirements.txt && \
-    pip3 install -r /src/cortex/tf_api/requirements.txt && \
+RUN pip install -r /src/cortex/lib/requirements.txt && \
+    pip install -r /src/cortex/tf_api/requirements.txt && \
     rm -rf /root/.cache/pip*
 
 COPY pkg/workloads/cortex/consts.py /src/cortex/
diff --git a/pkg/workloads/cortex/onnx_serve/run.sh b/pkg/workloads/cortex/onnx_serve/run.sh
index 729c676a76..54a601afdf 100755
--- a/pkg/workloads/cortex/onnx_serve/run.sh
+++ b/pkg/workloads/cortex/onnx_serve/run.sh
@@ -16,6 +16,6 @@
 
 
 if [ -f "/mnt/project/requirements.txt" ]; then
-    pip3 install -r /mnt/project/requirements.txt
+    pip install -r /mnt/project/requirements.txt
 fi
-/usr/bin/python3 /src/cortex/onnx_serve/api.py "$@"
+/usr/bin/python3.6 /src/cortex/onnx_serve/api.py "$@"
diff --git a/pkg/workloads/cortex/tf_api/run.sh b/pkg/workloads/cortex/tf_api/run.sh
index 802be7913a..b9a39ebbe9 100755
--- a/pkg/workloads/cortex/tf_api/run.sh
+++ b/pkg/workloads/cortex/tf_api/run.sh
@@ -16,6 +16,6 @@
 
 
 if [ -f "/mnt/project/requirements.txt" ]; then
-    pip3 install -r /mnt/project/requirements.txt
+    pip install -r /mnt/project/requirements.txt
 fi
-/usr/bin/python3 /src/cortex/tf_api/api.py "$@"
+/usr/bin/python3.6 /src/cortex/tf_api/api.py "$@"