diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 11da6c749f1d2888fecc2cf9ba0eab02eee55aea..a5dcf79205ce21b1c4b942889e780aae24c9826e 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -75,6 +75,8 @@ Python 3 POCL Firedrake Examples:
 Python 3 Conda:
   script: |
     CONDA_ENVIRONMENT=.test-conda-env-py3.yml
+    export MPLBACKEND=Agg
+
     curl -L -O -k https://gitlab.tiker.net/inducer/ci-support/raw/master/build-and-test-py-project-within-miniconda.sh
     . ./build-and-test-py-project-within-miniconda.sh
   tags: