diff --git a/.github/lint-scripts.sh b/.github/lint-scripts.sh
index d2c824a..7bf2204 100755
--- a/.github/lint-scripts.sh
+++ b/.github/lint-scripts.sh
@@ -5,12 +5,13 @@
 
 set -o errexit
 
-REPO_ROOT="$(git rev-parse --show-toplevel)"
 TMP_FILE="$(mktemp)"
 
-find "${REPO_ROOT}" -type f -name "*.sh" > "${TMP_FILE}"
+find . -type f -name "*.sh" > "${TMP_FILE}"
 
 while read -r FILE; do
   echo lint "${FILE}"
   shellcheck -x "${FILE}"
 done < "${TMP_FILE}"
+
+rm "${TMP_FILE}"
diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
index c1837a9..d87cfec 100644
--- a/.github/workflows/ci.yaml
+++ b/.github/workflows/ci.yaml
@@ -14,8 +14,15 @@ jobs:
         with:
           args: .github/lint-scripts.sh
 
+  lint-docker-files:
+    runs-on: ubuntu-latest
+    steps:
+      - name: lint zammad dockerfile
+        uses: brpaz/hadolint-action@master
+        with:
+          dockerfile: zammad/Dockerfile
+
   install-docker-compose:
-    name: install-docker-compose
     timeout-minutes: 30
     runs-on: ubuntu-latest
     needs: lint-bash-scripts