diff --git a/unittests/docker/Dockerfile b/unittests/docker/Dockerfile
index 06f9d6c830068a2c1c85caef79c64f899eaefb33..7c84050b0a55ae6e1e8f2e2583f894a69f691193 100644
--- a/unittests/docker/Dockerfile
+++ b/unittests/docker/Dockerfile
@@ -1,4 +1,4 @@
-FROM debian:latest
+FROM debian:bullseye
 # Use local package repository
 COPY sources.list.local /etc/apt/
 RUN mv /etc/apt/sources.list /etc/apt/sources.list.orig