diff --git a/hawk/processes/wps_causal.py b/hawk/processes/wps_causal.py
index b92d47b..feeb5a7 100644
--- a/hawk/processes/wps_causal.py
+++ b/hawk/processes/wps_causal.py
@@ -5,6 +5,7 @@
 import logging
 import pandas as pd
 from hawk.analysis import CausalAnalysis
+import os
 
 LOGGER = logging.getLogger("PYWPS")
 
@@ -234,6 +235,7 @@ def _handler(self, request, response):
         tefs_max_lag_target = int(request.inputs["tefs_max_lag_target"][0].data)
 
         workdir = Path(self.workdir)
+        os.environ['MPLCONFIGDIR'] = os.path.join(workdir, "/matplotlib")
 
         if not tefs_use_contemporary_features and tefs_max_lag_features == 0:
             raise ValueError("You cannot use no lag features and not use contemporary features in TEFS.")