diff --git a/Dockerfile b/Dockerfile
index 10408d25850f5a8c1c9ffbaa8a1d98915874d84d..685b0f72f1fc1bab4d8b16d31f9e0728ce843a1c 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -10,4 +10,4 @@ COPY . heros
 
 # Install HEROS in editable mode
 RUN pip install --break-system-packages -e heros/ && \
-    mkdir /git/custom && echo 'import sys\nsys.path.insert(0, "/git/custom")' > /usr/local/lib/`ls /usr/local/lib | grep -P ^python3\.[[:digit:]]+$`/site-packages/sitecustomize.py
+    mkdir /git/custom && echo 'import site\nsite.addsitedir("/git/custom")' > /usr/local/lib/`ls /usr/local/lib | grep -P ^python3\.[[:digit:]]+$`/site-packages/sitecustomize.py