diff --git a/build-support/docker/travis_ci_py27_ucs2/Dockerfile b/build-support/docker/travis_ci_py27_ucs2/Dockerfile
index fc87f53a81a..a3bd9df456b 100644
--- a/build-support/docker/travis_ci_py27_ucs2/Dockerfile
+++ b/build-support/docker/travis_ci_py27_ucs2/Dockerfile
@@ -23,6 +23,7 @@ RUN /usr/bin/scl enable devtoolset-7 -- bash -c '\
     && ${PYENV_ROOT}/bin/pyenv global ${PYTHON_2_VERSION}'
 ENV PATH "${PYENV_ROOT}/shims:${PATH}"
 ENV PY "${PYENV_ROOT}/shims/python2.7"
+ENV PEX_PYTHON "${PYENV_ROOT}/shims/python2.7"
 
 # Setup mount points for the travis ci user & workdir.
 VOLUME /travis/home