diff --git a/packages/worker/deb-build/Dockerfile b/packages/worker/deb-build/Dockerfile
index 9e450d8f..fb83c8ba 100644
--- a/packages/worker/deb-build/Dockerfile
+++ b/packages/worker/deb-build/Dockerfile
@@ -1,4 +1,4 @@
-FROM debian:bullseye-slim
+FROM debian:bookworm-slim
 WORKDIR /worker
 
 #suppress installation prompts
diff --git a/whisper_container/Dockerfile b/whisper_container/Dockerfile
index 97dd13b2..f8197569 100644
--- a/whisper_container/Dockerfile
+++ b/whisper_container/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:22.04
+FROM debian:bookworm-slim
 WORKDIR /opt
 LABEL com.theguardian.transcription-service.whisper-container="Whisper.cpp container with models downloaded, including ffmpeg"