diff --git a/docker/centos/Dockerfile b/docker/centos/Dockerfile
index 2ab56f2..a22276a 100644
--- a/docker/centos/Dockerfile
+++ b/docker/centos/Dockerfile
@@ -65,7 +65,7 @@ ENV LXR_DATA_DIR /srv/elixir-data/$PROJECT/data
 RUN \
   cd /usr/local/elixir/ && \
   ./script.sh list-tags && \
-  ./update.py
+  python3 -u ./update.py
 
 # apache elixir config, see elixir README
 # apache HttpProtolOptions workaround
diff --git a/docker/debian/Dockerfile b/docker/debian/Dockerfile
index 163ceae..f1adff5 100644
--- a/docker/debian/Dockerfile
+++ b/docker/debian/Dockerfile
@@ -57,7 +57,7 @@ ENV LXR_DATA_DIR /srv/elixir-data/$PROJECT/data
 RUN \
   cd /usr/local/elixir/ && \
   ./script.sh list-tags && \
-  ./update.py
+  python3 -u ./update.py
 
 # apache elixir config, see elixir README
 # make apache less stricter about cgitb spam headers