diff --git a/docker/matrix-eavesdrop/Dockerfile b/docker/matrix-eavesdrop/Dockerfile
index 92cc5e48c4..52cee9a7e5 100644
--- a/docker/matrix-eavesdrop/Dockerfile
+++ b/docker/matrix-eavesdrop/Dockerfile
@@ -14,11 +14,13 @@
 # limitations under the License.
 
 FROM docker.io/opendevorg/python-builder:3.9 as builder
+RUN echo 'deb http://deb.debian.org/debian buster-backports main' >> /etc/apt/sources.list
 
 COPY src /tmp/src
 RUN assemble
 
 FROM docker.io/opendevorg/python-base:3.9 as eavesdrop
+RUN echo 'deb http://deb.debian.org/debian buster-backports main' >> /etc/apt/sources.list
 
 COPY --from=builder /output/ /output
 RUN /output/install-from-bindep \
diff --git a/docker/matrix-eavesdrop/src/bindep.txt b/docker/matrix-eavesdrop/src/bindep.txt
index e65b421f3f..16b91ae828 100644
--- a/docker/matrix-eavesdrop/src/bindep.txt
+++ b/docker/matrix-eavesdrop/src/bindep.txt
@@ -1,7 +1,7 @@
 gcc [compile test]
 libc6-dev [compile test]
 libffi-dev [compile test]
-libolm-dev [compile test]
+libolm-dev/buster-backports [compile test]
 make [compile test]
 python3-dev [compile test]
-libolm3
+libolm3/buster-backports
diff --git a/docker/python-base/Dockerfile b/docker/python-base/Dockerfile
index 01c720a10d..3c246aca07 100644
--- a/docker/python-base/Dockerfile
+++ b/docker/python-base/Dockerfile
@@ -16,15 +16,14 @@
 # Comment to force rebuilds Tue Aug  3 19:59:32 UTC 2021
 
 ARG PYTHON_VERSION=3.7
-FROM docker.io/library/python:${PYTHON_VERSION}-slim
+FROM docker.io/library/python:${PYTHON_VERSION}-slim-buster
 
 RUN echo 'APT::Install-Recommends "0";' > /etc/apt/apt.conf.d/95disable-recommends
 
 RUN apt-get update \
   && apt-get install -y dumb-init \
   && apt-get clean \
-  && rm -rf /var/lib/apt/lists/* \
-  && echo 'deb http://deb.debian.org/debian bullseye-backports main' >> /etc/apt/sources.list
+  && rm -rf /var/lib/apt/lists/*
 
 # Upgrade pip to fix wheel cache for locally built wheels.
 # See https://github.com/pypa/pip/issues/6852
diff --git a/docker/python-builder/Dockerfile b/docker/python-builder/Dockerfile
index d31dabfa5d..e03aee6df8 100644
--- a/docker/python-builder/Dockerfile
+++ b/docker/python-builder/Dockerfile
@@ -16,7 +16,7 @@
 # Comment to force rebuilds Tue Aug  3 19:59:32 UTC 2021
 
 ARG PYTHON_VERSION=3.7
-FROM docker.io/library/python:${PYTHON_VERSION}-slim as fake-python
+FROM docker.io/library/python:${PYTHON_VERSION}-slim-buster as fake-python
 
 WORKDIR /tmp
 RUN apt-get update \
@@ -25,7 +25,7 @@ RUN apt-get update \
 COPY python3-dev.control /tmp/python3-dev.control
 RUN equivs-build /tmp/python3-dev.control
 
-FROM docker.io/library/python:${PYTHON_VERSION}-slim
+FROM docker.io/library/python:${PYTHON_VERSION}-slim-buster
 
 RUN echo 'APT::Install-Recommends "0";' > /etc/apt/apt.conf.d/95disable-recommends
 
@@ -36,8 +36,7 @@ COPY scripts/install-from-bindep /output/install-from-bindep
 RUN dpkg -i /tmp/python3-dev_4.0.0_all.deb \
   && rm /tmp/python3-dev_4.0.0_all.deb \
   && pip install --no-cache-dir bindep \
-  && rm -rf /var/lib/apt/lists/* \
-  && echo 'deb http://deb.debian.org/debian bullseye-backports main' >> /etc/apt/sources.list
+  && rm -rf /var/lib/apt/lists/*
 
 # Upgrade pip to fix wheel cache for locally built wheels
 # See https://github.com/pypa/pip/issues/6852
diff --git a/docker/uwsgi-base/bindep.txt b/docker/uwsgi-base/bindep.txt
index db53d4bea3..670f7d05a7 100644
--- a/docker/uwsgi-base/bindep.txt
+++ b/docker/uwsgi-base/bindep.txt
@@ -1,5 +1,5 @@
 gcc [compile]
 libc6-dev [compile]
 libffi-dev [compile platform:dpkg]
-libffi7 [platform:dpkg]
+libffi6 [platform:dpkg]
 libssl-dev [compile platform:dpkg]