diff --git a/setup.py b/setup.py
index 915391a4ac..5de6018568 100644
--- a/setup.py
+++ b/setup.py
@@ -71,6 +71,7 @@ setup(
     },
     extras_require={
         'backend': ['onnx>=1.2.3'],
+        'numpy': ['numpy>=1.15.0']
     },
     entry_points= {
         'console_scripts': [
diff --git a/tools/ci_build/build.py b/tools/ci_build/build.py
index f3ff664d2d..24f786a61d 100755
--- a/tools/ci_build/build.py
+++ b/tools/ci_build/build.py
@@ -196,7 +196,7 @@ def install_ubuntu_deps(args):
             raise BuildError("Error setting up required APT packages. {}".format(str(e)))
 
 def install_python_deps():
-    dep_packages = ['setuptools', 'wheel', 'numpy']
+    dep_packages = ['setuptools', 'wheel', 'numpy==1.15.0']
     run_subprocess([sys.executable, '-m', 'pip', 'install', '--trusted-host', 'files.pythonhosted.org'] + dep_packages)
 
 def check_md5(filename, expected_md5):
diff --git a/tools/ci_build/github/azure-pipelines/azure-pipelines-py-packaging.yml b/tools/ci_build/github/azure-pipelines/azure-pipelines-py-packaging.yml
index fa9aaff75d..a507400934 100644
--- a/tools/ci_build/github/azure-pipelines/azure-pipelines-py-packaging.yml
+++ b/tools/ci_build/github/azure-pipelines/azure-pipelines-py-packaging.yml
@@ -196,7 +196,7 @@ jobs:
         cleanEnvironment: true
 
     - script: |
-        sudo python -m pip install numpy
+        sudo python -m pip install numpy==1.15.0
         sudo xcode-select --switch /Applications/Xcode_10.app/Contents/Developer
         ./build.sh --config Release --skip_submodule_sync --parallel --use_openmp --build_wheel
       displayName: 'Command Line Script'
diff --git a/tools/ci_build/github/linux/docker/scripts/install_ubuntu.sh b/tools/ci_build/github/linux/docker/scripts/install_ubuntu.sh
index 823937bce0..4713591024 100755
--- a/tools/ci_build/github/linux/docker/scripts/install_ubuntu.sh
+++ b/tools/ci_build/github/linux/docker/scripts/install_ubuntu.sh
@@ -7,6 +7,7 @@ p) PYTHON_VER=${OPTARG};;
 esac
 done
 
+PYTHON_VER=${PYTHON_VER:=3.5}
 DEBIAN_FRONTEND=noninteractive
 
 apt-get update && apt-get install -y software-properties-common
@@ -52,16 +53,16 @@ apt-get update
 apt-get install -y dotnet-sdk-2.2
 rm -rf /tmp/dotnet || true
 
-if [ $PYTHON_VER != "3.5" ]; then
+if [ $PYTHON_VER!="3.5" ]; then
     apt-get install -y --no-install-recommends \
             python${PYTHON_VER} \
             python${PYTHON_VER}-dev
     update-alternatives --install /usr/bin/python3 python3 /usr/bin/python${PYTHON_VER} 1
     update-alternatives --install /usr/bin/python3 python3 /usr/bin/python3.5 2
     update-alternatives --set python3 /usr/bin/python${PYTHON_VER}
-    /usr/bin/python${PYTHON_VER} -m pip install --upgrade --force-reinstall numpy
 fi
 
+/usr/bin/python${PYTHON_VER} -m pip install --upgrade --force-reinstall numpy==1.15.0
 rm -rf /var/lib/apt/lists/*
 
 mkdir -p /tmp/azcopy