diff --git a/Dockerfile b/Dockerfile
index 622b2e8..c08bd46 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,7 +1,8 @@
 FROM ubuntu:20.04
 
 # Based on
-# https://switch2osm.org/serving-tiles/manually-building-a-tile-server-18-04-lts/
+# https://switch2osm.org/serving-tiles/manually-building-a-tile-server-20-04-lts/
+# https://github.com/Overv/openstreetmap-tile-server
 
 # Set up environment
 ENV TZ=UTC
@@ -160,7 +161,7 @@ COPY leaflet-demo.html /var/www/html/index.html
 RUN ln -sf /dev/stdout /var/log/apache2/access.log \
  && ln -sf /dev/stderr /var/log/apache2/error.log \
  && sed -i -e 's/80/8080/g' /etc/apache2/ports.conf \
- && sed -i -e 's/80/8080/g' /etc/apache2/sites-available/* \
+ && sed -i -e 's/80/8080/g' /etc/apache2/sites-available/* 
  
 # Configure Varnish
 RUN systemctl start varnish \