diff --git a/client/Dockerfile b/client/Dockerfile
index 45d06f4..720860d 100644
--- a/client/Dockerfile
+++ b/client/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.14.3-slim
+FROM python:3.15.0a8-slim
 
 ENV DEVPICLIENT_CLIENTDIR=/devpi/client
 RUN mkdir -p $DEVPICLIENT_CLIENTDIR
diff --git a/client/Dockerfile-alpine b/client/Dockerfile-alpine
index 0855b22..48be184 100644
--- a/client/Dockerfile-alpine
+++ b/client/Dockerfile-alpine
@@ -1,4 +1,4 @@
-FROM python:3.14.3-alpine
+FROM python:3.15.0a8-alpine
 
 ENV DEVPICLIENT_CLIENTDIR=/devpi/client
 RUN mkdir -p $DEVPICLIENT_CLIENTDIR