diff --git a/ci/alpine/Dockerfile b/ci/alpine/Dockerfile
index 61890c41d6..afd72835f2 100644
--- a/ci/alpine/Dockerfile
+++ b/ci/alpine/Dockerfile
@@ -1,5 +1,9 @@
 FROM alpine:latest
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apk add --no-cache \
   ccache \
   cmake \
diff --git a/ci/centos-7/Dockerfile b/ci/centos-7/Dockerfile
index 2b03584eab..73135cc521 100644
--- a/ci/centos-7/Dockerfile
+++ b/ci/centos-7/Dockerfile
@@ -1,5 +1,9 @@
 FROM centos:7
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 ENV FLEX_VERSION=2.6.4
 ENV FLEX_DIR=/opt/flex
 
diff --git a/ci/centos-stream-8/Dockerfile b/ci/centos-stream-8/Dockerfile
index b1d950e63c..db2e8adeb7 100644
--- a/ci/centos-stream-8/Dockerfile
+++ b/ci/centos-stream-8/Dockerfile
@@ -1,5 +1,9 @@
 FROM quay.io/centos/centos:stream8
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN dnf -y install https://dl.fedoraproject.org/pub/epel/epel-release-latest-8.noarch.rpm
 RUN dnf config-manager --set-enabled powertools
 
diff --git a/ci/centos-stream-9/Dockerfile b/ci/centos-stream-9/Dockerfile
index 435df82a66..0973443e44 100644
--- a/ci/centos-stream-9/Dockerfile
+++ b/ci/centos-stream-9/Dockerfile
@@ -1,5 +1,9 @@
 FROM quay.io/centos/centos:stream9
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 # dnf config-manager isn't available at first, and
 # we need it to install the CRB repo below.
 RUN dnf -y install 'dnf-command(config-manager)'
diff --git a/ci/debian-10/Dockerfile b/ci/debian-10/Dockerfile
index 4dfeaef799..f384263c3e 100644
--- a/ci/debian-10/Dockerfile
+++ b/ci/debian-10/Dockerfile
@@ -2,6 +2,10 @@ FROM debian:10
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"
 
diff --git a/ci/debian-11/Dockerfile b/ci/debian-11/Dockerfile
index 007fefb9d6..905f014521 100644
--- a/ci/debian-11/Dockerfile
+++ b/ci/debian-11/Dockerfile
@@ -2,6 +2,10 @@ FROM debian:11
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     ccache \
     git \
diff --git a/ci/debian-9-32bit/Dockerfile b/ci/debian-9-32bit/Dockerfile
index b321ac3b86..197fe28e27 100644
--- a/ci/debian-9-32bit/Dockerfile
+++ b/ci/debian-9-32bit/Dockerfile
@@ -4,7 +4,7 @@ ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
 # A version field to invalide Cirrus's build cache when needed, as suggested in
 # https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
-ENV DOCKERFILE_VERSION 221001
+ENV DOCKERFILE_VERSION 20220519
 
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"
diff --git a/ci/debian-9/Dockerfile b/ci/debian-9/Dockerfile
index b3eb66593d..f59a333be4 100644
--- a/ci/debian-9/Dockerfile
+++ b/ci/debian-9/Dockerfile
@@ -4,7 +4,7 @@ ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
 # A version field to invalide Cirrus's build cache when needed, as suggested in
 # https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
-ENV DOCKERFILE_VERSION 221001
+ENV DOCKERFILE_VERSION 20220519
 
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"
diff --git a/ci/fedora-34/Dockerfile b/ci/fedora-34/Dockerfile
index 10f4ae3aaa..1b75243206 100644
--- a/ci/fedora-34/Dockerfile
+++ b/ci/fedora-34/Dockerfile
@@ -1,5 +1,9 @@
 FROM fedora:34
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN dnf -y install \
     ccache \
     bison \
diff --git a/ci/fedora-35/Dockerfile b/ci/fedora-35/Dockerfile
index e242fb95a7..7a3c6fe3a5 100644
--- a/ci/fedora-35/Dockerfile
+++ b/ci/fedora-35/Dockerfile
@@ -1,5 +1,9 @@
 FROM fedora:35
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN dnf -y install \
     ccache \
     bison \
diff --git a/ci/openssl-3.0/Dockerfile b/ci/openssl-3.0/Dockerfile
index cb276c1e0d..98f9598b9b 100644
--- a/ci/openssl-3.0/Dockerfile
+++ b/ci/openssl-3.0/Dockerfile
@@ -2,6 +2,10 @@ FROM ubuntu:20.04
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     ccache \
     git \
diff --git a/ci/opensuse-leap-15.3/Dockerfile b/ci/opensuse-leap-15.3/Dockerfile
index 3e4708f66b..36eed15c1e 100644
--- a/ci/opensuse-leap-15.3/Dockerfile
+++ b/ci/opensuse-leap-15.3/Dockerfile
@@ -1,5 +1,9 @@
 FROM opensuse/leap:15.3
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN zypper addrepo https://download.opensuse.org/repositories/openSUSE:Leap:15.2:Update/standard/openSUSE:Leap:15.2:Update.repo \
  && zypper refresh \
  && zypper in -y \
diff --git a/ci/ubuntu-18.04/Dockerfile b/ci/ubuntu-18.04/Dockerfile
index 2b9f7f43ad..56c50eb6ae 100644
--- a/ci/ubuntu-18.04/Dockerfile
+++ b/ci/ubuntu-18.04/Dockerfile
@@ -2,6 +2,10 @@ FROM ubuntu:18.04
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 ENV CMAKE_DIR "/opt/cmake"
 ENV CMAKE_VERSION "3.19.1"
 ENV PATH "${CMAKE_DIR}/bin:${PATH}"
diff --git a/ci/ubuntu-20.04/Dockerfile b/ci/ubuntu-20.04/Dockerfile
index 0b9d46a13a..aaad8182ba 100644
--- a/ci/ubuntu-20.04/Dockerfile
+++ b/ci/ubuntu-20.04/Dockerfile
@@ -2,6 +2,10 @@ FROM ubuntu:20.04
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     ccache \
     git \
diff --git a/ci/ubuntu-21.10/Dockerfile b/ci/ubuntu-21.10/Dockerfile
index a36f196323..27005e95d9 100644
--- a/ci/ubuntu-21.10/Dockerfile
+++ b/ci/ubuntu-21.10/Dockerfile
@@ -2,6 +2,10 @@ FROM ubuntu:21.10
 
 ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
+# A version field to invalide Cirrus's build cache when needed, as suggested in
+# https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
+ENV DOCKERFILE_VERSION 20220519
+
 RUN apt-get update && apt-get -y install \
     git \
     ccache \