diff --git a/Dockerfile b/Dockerfile
index 0b35054..bdbaf63 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,5 +1,5 @@
 # Dockerfile
-FROM pretix/standalone:stable
+FROM pretix/standalone:4.20.4
 
 USER pretixuser
 RUN PYTHONPATH=$PYTHONPATH:/pretix/src pip3 install pretix-ldap