diff --git a/Dockerfile.python b/Dockerfile.python
index 7097a40ab3c366a40ca5160fd1dca27798cf75ef..fb43c2ee81e7932178d483980a022ba7d7c9a47c 100644
--- a/Dockerfile.python
+++ b/Dockerfile.python
@@ -58,3 +58,6 @@ RUN chown shiny:shiny /var/lib/shiny-server \
  && chown shiny:shiny /var/log/shiny-server \
  && mkdir -p /srv/shiny-server/www \
  && chown shiny:shiny /srv/shiny-server/www
+
+# When a lib uses QT (such as ETE3), it can fail to load as there is no X11
+ENV QT_QPA_PLATFORM=offscreen