diff --git a/docker-compose.yml b/docker-compose.yml
index dd7892e..8711f38 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -32,9 +32,13 @@ services:
     <<: *image
     command: ["mavsttd", "-socket", "/run/maven/stt.sock", "-model", "/opt/maven/models/stt/ggml-small.bin"]
     depends_on: [mavend]
-    # whisper uses libggml-vulkan → needs the GPU render node.
+    # whisper uses libggml-vulkan (RADV on the host's AMD GPU) → needs the
+    # render node AND membership in the group that owns it, or Vulkan enumerates
+    # zero devices and falls back to CPU.
     devices:
       - "/dev/dri:/dev/dri"
+    group_add:
+      - "993"   # host 'render' gid owning /dev/dri/renderD128 (getent group render)
     volumes:
       - sockets:/run/maven
       - ./models:/opt/maven/models:ro