diff --git a/docker/Dockerfile-optimised b/docker/Dockerfile-optimised
index dc6828a20..c9e6b4b2a 100644
--- a/docker/Dockerfile-optimised
+++ b/docker/Dockerfile-optimised
@@ -53,7 +53,7 @@ RUN chown -R root:root /usr/local /install
 FROM matrixdotorg/optimised-python:${PYTHON_VERSION}-optimized-lto-${MARCH}
 
 # xmlsec is required for saml support
-RUN apt-get update && apt-get install -y libpq5 xmlsec libxslt1
+RUN apt-get update && apt-get install -y libpq5 xmlsec1 libxslt1.1
 
 COPY --from=builder /install /usr/local
 COPY ./docker/start.py /start.py