diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 9eeffdc..82c85db 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -8,6 +8,8 @@ compile_pdf:
 
 data_processing:
   image: python_datascience
+  variables:
+    MPLBACKEND: agg
   script:
     - cd data && python3 processing.py
   artifacts: