diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index 3d54b9a3..232f88b8 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -108,6 +108,9 @@ jobs:
           tag=latest
           [[ ! "$version" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]] && tag=main
           docker push grafana/carbon-relay-ng:$tag
+          # To preserve compatibility, also push the "master" tag we built in
+          # build_docker.sh.
+          [[ "$tag" == "main" ]] && docker push grafana/carbon-relay-ng:master
 
   github_binaries:
     if: github.ref_type == 'tag'
diff --git a/build_docker.sh b/build_docker.sh
index 1106d58e..c3370bf6 100755
--- a/build_docker.sh
+++ b/build_docker.sh
@@ -10,3 +10,8 @@ tag=main
 
 docker build --tag=grafana/carbon-relay-ng:$tag .
 docker tag grafana/carbon-relay-ng:$tag grafana/carbon-relay-ng:$version
+
+# To preserve compatibility with older installations, also tag "master" when we tag "main".
+if [ "$tag" == "main" ] ; then
+  docker tag grafana/carbon-relay-ng:$tag grafana/carbon-relay-ng:master
+fi