diff --git a/pyspark-notebook/Dockerfile b/pyspark-notebook/Dockerfile
index 5106c820..e141422a 100644
--- a/pyspark-notebook/Dockerfile
+++ b/pyspark-notebook/Dockerfile
@@ -70,3 +70,4 @@ RUN mamba install --quiet --yes \
     fix-permissions "/home/${NB_USER}"
 
 WORKDIR "${HOME}"
+EXPOSE 4040