diff --git a/ci/docker/bionic b/ci/docker/bionic
index fb6a34b1c..51af5c01c 100644
--- a/ci/docker/bionic
+++ b/ci/docker/bionic
@@ -1,4 +1,5 @@
 ARG BASE=ubuntu:bionic
+
 FROM ${BASE} AS apt
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
diff --git a/ci/docker/centos7 b/ci/docker/centos7
index 082b9e225..098edb26a 100644
--- a/ci/docker/centos7
+++ b/ci/docker/centos7
@@ -1,4 +1,5 @@
 ARG BASE=centos:7
+
 FROM ${BASE} AS yum
 RUN yum install -y \
 	which \
diff --git a/ci/docker/centos8 b/ci/docker/centos8
index e1fb7684a..f47198446 100644
--- a/ci/docker/centos8
+++ b/ci/docker/centos8
@@ -1,4 +1,5 @@
 ARG BASE=centos:8
+
 FROM ${BASE} AS yum
 RUN yum install -y \
 	which \
diff --git a/ci/docker/docurium b/ci/docker/docurium
index 7aa247532..1957bbb3b 100644
--- a/ci/docker/docurium
+++ b/ci/docker/docurium
@@ -1,4 +1,5 @@
 ARG BASE=ubuntu:bionic
+
 FROM ${BASE}
 RUN apt update && apt install -y cmake pkg-config ruby ruby-dev llvm libclang-dev libssl-dev python-pygments
 RUN gem install docurium
diff --git a/ci/docker/focal b/ci/docker/focal
index c0c57f640..171387698 100644
--- a/ci/docker/focal
+++ b/ci/docker/focal
@@ -1,4 +1,5 @@
 ARG BASE=ubuntu:focal
+
 FROM ${BASE} AS apt
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
diff --git a/ci/docker/xenial b/ci/docker/xenial
index d2ba0313f..4c3810af4 100644
--- a/ci/docker/xenial
+++ b/ci/docker/xenial
@@ -1,4 +1,5 @@
 ARG BASE=ubuntu:xenial
+
 FROM ${BASE} AS apt
 RUN apt-get update && \
     DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \