diff --git a/3.4/onbuild/Dockerfile b/3.4/onbuild/Dockerfile
index f0d01721c..2704da40d 100644
--- a/3.4/onbuild/Dockerfile
+++ b/3.4/onbuild/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.4
+FROM python:3.9
 
 RUN mkdir -p /usr/src/app
 WORKDIR /usr/src/app