diff --git a/tools/run_tests/helper_scripts/build_python.sh b/tools/run_tests/helper_scripts/build_python.sh
index 6f34c912904..be802112493 100755
--- a/tools/run_tests/helper_scripts/build_python.sh
+++ b/tools/run_tests/helper_scripts/build_python.sh
@@ -168,6 +168,14 @@ pip_install_dir() {
   cd "$PWD"
 }
 
+pip_install_dir_and_deps() {
+  PWD=$(pwd)
+  cd "$1"
+  ($VENV_PYTHON setup.py build_ext -c "$TOOLCHAIN" || true)
+  $VENV_PYTHON -m pip install .
+  cd "$PWD"
+}
+
 # Install gevent
 if [[ "$VENV" == "py36" ]]; then
   # TODO(https://github.com/grpc/grpc/issues/15411) unpin this
@@ -187,7 +195,7 @@ fi
 pip_install_dir "$ROOT"
 
 $VENV_PYTHON "$ROOT/tools/distrib/python/make_grpcio_tools.py"
-pip_install_dir "$ROOT/tools/distrib/python/grpcio_tools"
+pip_install_dir_and_deps "$ROOT/tools/distrib/python/grpcio_tools"
 
 # Build/install Channelz
 $VENV_PYTHON "$ROOT/src/python/grpcio_channelz/setup.py" preprocess