diff --git a/docs/source/conf.py b/docs/source/conf.py
index 91cbb1a5c..5d35ac904 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -44,6 +44,7 @@
     "h5py",
     "hdf5plugin",
     "httomo_backends",
+    "PIL",
     "scipy",
     "scipy.signal",
 ]