diff --git a/.github/workflows/docker-publish.yml b/.github/workflows/docker-publish.yml
index 2cb8221ec..6865d5120 100644
--- a/.github/workflows/docker-publish.yml
+++ b/.github/workflows/docker-publish.yml
@@ -29,7 +29,6 @@ permissions:
 
 env:
   REGISTRY: ghcr.io
-  IMAGE_NAME: ${{ github.repository }}
 
 jobs:
   build:
@@ -52,6 +51,9 @@ jobs:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
         with:
           persist-credentials: false
+      - name: Normalize image name
+        shell: bash
+        run: echo "IMAGE_NAME=${GITHUB_REPOSITORY,,}" >> "$GITHUB_ENV"
       - name: Set up Buildx
         uses: docker/setup-buildx-action@37fe631027851001ddb9b187196cc803df7f5f0e  # v4.3.0
       - name: Log in to GHCR
@@ -94,6 +96,9 @@ jobs:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7.0.1
         with:
           persist-credentials: false
+      - name: Normalize image name
+        shell: bash
+        run: echo "IMAGE_NAME=${GITHUB_REPOSITORY,,}" >> "$GITHUB_ENV"
       - name: Read APP_VERSION + short sha
         id: ver
         run: |
diff --git a/tests/test_docker_publish_image_name.py b/tests/test_docker_publish_image_name.py
new file mode 100644
index 000000000..6b6613c52
--- /dev/null
+++ b/tests/test_docker_publish_image_name.py
@@ -0,0 +1,63 @@
+"""Execute the publication workflow's image-name setup without contacting GHCR."""
+
+import os
+import shutil
+import subprocess
+from pathlib import Path
+
+import pytest
+import yaml
+
+
+WORKFLOW = (
+    Path(__file__).resolve().parents[1]
+    / ".github"
+    / "workflows"
+    / "docker-publish.yml"
+)
+
+
+@pytest.mark.skipif(shutil.which("bash") is None, reason="Docker publication requires Bash")
+@pytest.mark.parametrize("job", ["build", "merge"])
+@pytest.mark.parametrize(
+    ("repository", "expected"),
+    [
+        ("RaresKeY/odysseus-dev", "rareskey/odysseus-dev"),
+        ("ExampleOwner/Example-Repo", "exampleowner/example-repo"),
+        ("odysseus-dev/odysseus", "odysseus-dev/odysseus"),
+    ],
+)
+def test_image_name_is_lowercase_before_docker_steps(tmp_path, job, repository, expected):
+    workflow = yaml.safe_load(WORKFLOW.read_text(encoding="utf-8"))
+    image_name = workflow["env"].get("IMAGE_NAME", "").replace(
+        "${{ github.repository }}", repository
+    )
+    github_env = tmp_path / "github-env"
+    env = {
+        "PATH": os.environ["PATH"],
+        "GITHUB_REPOSITORY": repository,
+        "GITHUB_ENV": str(github_env),
+        "GITHUB_OUTPUT": str(tmp_path / "github-output"),
+        "GITHUB_SHA": "a" * 40,
+    }
+
+    # Run the real setup shell before the job starts using Docker actions.
+    # Checkout, login, builds and registry publication are deliberately excluded.
+    for step in workflow["jobs"][job]["steps"]:
+        if step.get("uses", "").startswith("docker/"):
+            break
+        if "run" not in step:
+            continue
+        subprocess.run(
+            ["bash", "--noprofile", "--norc", "-e", "-o", "pipefail", "-c", step["run"]],
+            cwd=WORKFLOW.parents[2],
+            env=env,
+            check=True,
+            capture_output=True,
+            text=True,
+        )
+        if github_env.exists():
+            env.update(line.split("=", 1) for line in github_env.read_text().splitlines())
+            image_name = env.get("IMAGE_NAME", image_name)
+
+    assert image_name == expected