diff --git a/client/Dockerfile b/client/Dockerfile
index d810051..e252bc0 100644
--- a/client/Dockerfile
+++ b/client/Dockerfile
@@ -1,4 +1,4 @@
-FROM python:3.14.6-slim
+FROM python:3.15.0rc1-slim
 
 ENV DEVPICLIENT_CLIENTDIR=/devpi/client
 RUN mkdir -p $DEVPICLIENT_CLIENTDIR
diff --git a/client/Dockerfile-alpine b/client/Dockerfile-alpine
index 14071c4..6861d69 100644
--- a/client/Dockerfile-alpine
+++ b/client/Dockerfile-alpine
@@ -1,4 +1,4 @@
-FROM python:3.14.6-alpine
+FROM python:3.15.0rc1-alpine
 
 ENV DEVPICLIENT_CLIENTDIR=/devpi/client
 RUN mkdir -p $DEVPICLIENT_CLIENTDIR