diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 34ebe33ae273291063fc884cb3bd4d157271a499..8ec4e2344bd54b6705cf1ccecbaeef2a1fa54571 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 cython numpy mako mpi4py"
   # cython is here because pytential (for now, for TS) depends on it
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
@@ -36,7 +36,7 @@ Python 3 Nvidia K40:
 Python 3 POCL:
   script:
   - export PY_EXE=python3
-  - export PYOPENCL_TEST=portable
+  - export PYOPENCL_TEST=portable:pthread
   # cython is here because pytential (for now, for TS) depends on it
   - export EXTRA_INSTALL="pybind11 cython numpy mako mpi4py"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh
@@ -54,7 +54,7 @@ Python 3 POCL:
 Python 3 POCL:
   script:
   - export PY_EXE=python3
-  - export PYOPENCL_TEST=portable
+  - export PYOPENCL_TEST=portable:pthread
   # cython is here because pytential (for now, for TS) depends on it
   - export EXTRA_INSTALL="pybind11 cython numpy mako mpi4py"
   - curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project.sh