diff --git a/ci/ubuntu-20.04/Dockerfile b/ci/ubuntu-20.04/Dockerfile
index be76b33005..38a68aa196 100644
--- a/ci/ubuntu-20.04/Dockerfile
+++ b/ci/ubuntu-20.04/Dockerfile
@@ -4,7 +4,7 @@ ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
 # A version field to invalidate Cirrus's build cache when needed, as suggested in
 # https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
-ENV DOCKERFILE_VERSION 20230801
+ENV DOCKERFILE_VERSION 20240528
 
 RUN apt-get update && apt-get -y install \
     bc \
@@ -36,4 +36,3 @@ RUN apt-get update && apt-get -y install \
   && rm -rf /var/lib/apt/lists/*
 
 RUN pip3 install websockets junit2html
-RUN gem install coveralls-lcov
diff --git a/ci/ubuntu-24.04/Dockerfile b/ci/ubuntu-24.04/Dockerfile
index fb6ddb477f..5aa2daa00e 100644
--- a/ci/ubuntu-24.04/Dockerfile
+++ b/ci/ubuntu-24.04/Dockerfile
@@ -4,7 +4,7 @@ ENV DEBIAN_FRONTEND="noninteractive" TZ="America/Los_Angeles"
 
 # A version field to invalidate Cirrus's build cache when needed, as suggested in
 # https://github.com/cirruslabs/cirrus-ci-docs/issues/544#issuecomment-566066822
-ENV DOCKERFILE_VERSION 20240508
+ENV DOCKERFILE_VERSION 20240528
 
 RUN apt-get update && apt-get -y install \
     bc \
@@ -39,3 +39,4 @@ RUN apt-get update && apt-get -y install \
   && rm -rf /var/lib/apt/lists/*
 
 RUN pip3 install --break-system-packages junit2html
+RUN gem install coveralls-lcov