diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index c059c7a92c38135ef24ca83ac4a5cb48dfebea82..75d22eac0b290d112cf0a27071e71f7bc8353afa 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,7 +1,7 @@
 Python 2.7 POCL:
   script:
   - export PY_EXE=python2.7
-  - export PYOPENCL_TEST=portable
+  - export PYOPENCL_TEST=portable:pthread
   - export EXTRA_INSTALL="pybind11 numpy mako"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
   - ". ./build-and-test-py-project.sh"
@@ -20,7 +20,7 @@ Python 2.7 POCL:
 Python 3 POCL:
   script:
   - export PY_EXE=python3
-  - export PYOPENCL_TEST=portable
+  - export PYOPENCL_TEST=portable:pthread
   - export EXTRA_INSTALL="pybind11 numpy mako"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
   - ". ./build-and-test-py-project.sh"
@@ -57,7 +57,7 @@ Python 3 Intel:
 Python 2.7 POCL MPI:
   script:
   - export PY_EXE=python2.7
-  - export PYOPENCL_TEST=portable
+  - export PYOPENCL_TEST=portable:pthread
   - export EXTRA_INSTALL="pybind11 numpy mako mpi4py pymetis"
   - export PYTEST_ADDOPTS="-k mpi"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
@@ -77,7 +77,7 @@ Python 2.7 POCL MPI:
 Python 3 POCL MPI:
   script:
   - export PY_EXE=python3
-  - export PYOPENCL_TEST=portable
+  - export PYOPENCL_TEST=portable:pthread
   - export EXTRA_INSTALL="pybind11 numpy mako mpi4py pymetis"
   - export PYTEST_ADDOPTS="-k mpi"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
@@ -116,7 +116,7 @@ Python 3 Intel MPI:
 Python 3 POCL Examples:
   script:
   - export PY_EXE=python3
-  - export PYOPENCL_TEST=portable
+  - export PYOPENCL_TEST=portable:pthread
   - export EXTRA_INSTALL="pybind11 numpy mako mpi4py pyvisfile pymetis"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-py-project-and-run-examples.sh
   - ". ./build-py-project-and-run-examples.sh"