diff --git a/Dockerfile.runtime b/Dockerfile.runtime
index 23bc9fc..c6eeb48 100644
--- a/Dockerfile.runtime
+++ b/Dockerfile.runtime
@@ -22,7 +22,10 @@ RUN apt-get update \
  && rm -rf /var/lib/apt/lists/*
 
 # ── Runtime stage ─────────────────────────────────────────────────────────────
-FROM --platform=linux/amd64 mcr.microsoft.com/dotnet/aspnet:10.0
+# .NET 9 runtime: matches the SDK 9.0 publish step (framework-dependent), so the
+# app's required Microsoft.NETCore.App 9.0 is present. Keep in lockstep with the
+# `mcr.microsoft.com/dotnet/sdk` major in .woodpecker/*.yaml and the Makefile.
+FROM --platform=linux/amd64 mcr.microsoft.com/dotnet/aspnet:9.0
 
 # FFmpeg and the native deps required by SkiaSharp and fontconfig.
 RUN apt-get update \
diff --git a/README.md b/README.md
index cb90dde..113000b 100644
--- a/README.md
+++ b/README.md
@@ -4,12 +4,12 @@ Build-orchestration repo for [ZoltyMat/jellyfin-ha](https://github.com/ZoltyMat/
 that adds distributed, Redis-backed transcoding for multi-pod Kubernetes (lease-aware cleanup, HA session
 takeover, optional PostgreSQL).
 
-This repo does **not** vendor the fork's source. It pins an upstream commit, builds the .NET 10 server, and
+This repo does **not** vendor the fork's source. It pins an upstream commit, builds the .NET 9 server, and
 produces a runtime container image pushed to the Gitea registry.
 
 ## What it produces
 
-`artifactapi.k8s.syd1.au.unkin.net/docker-internal/jellyfin-ha:<tag>` — an `mcr.microsoft.com/dotnet/aspnet:10.0` based image with ffmpeg and
+`artifactapi.k8s.syd1.au.unkin.net/docker-internal/jellyfin-ha:<tag>` — an `mcr.microsoft.com/dotnet/aspnet:9.0` based image with ffmpeg and
 the prebuilt `jellyfin-web` client, running the published `jellyfin-ha` server.
 
 ## Layout
@@ -34,7 +34,7 @@ the prebuilt `jellyfin-web` client, running the published `jellyfin-ha` server.
 make build            # clones pinned upstream, dotnet publish, docker build
 ```
 
-Requires the .NET 10 SDK and Docker. `make publish` runs just the clone + publish into `./publish-output`.
+Requires the .NET 9 SDK and Docker. `make publish` runs just the clone + publish into `./publish-output`.
 
 ## Deployment