diff --git a/.gitea/workflows/ci.yml b/.gitea/workflows/ci.yml
index 929db22..cb05809 100644
--- a/.gitea/workflows/ci.yml
+++ b/.gitea/workflows/ci.yml
@@ -40,7 +40,7 @@ jobs:
           password: ${{ secrets.TOKEN }}
 
       - name: Compute short SHA
-        run: echo "SHORT_SHA=${GITEA_SHA::7}" >> $GITEA_ENV
+        run: echo "SHORT_SHA=$(git rev-parse --short HEAD)" >> $GITEA_ENV
 
       - name: Build and push
         uses: docker/build-push-action@v5
diff --git a/tests/helpers.test.js b/tests/helpers.test.js
index a2af546..26bdd4d 100644
--- a/tests/helpers.test.js
+++ b/tests/helpers.test.js
@@ -156,4 +156,11 @@ describe('CI workflow regressions', () => {
     // BUILD_VERSION was never passed to docker build.
     expect(ciYml).toContain('BUILD_VERSION')
   })
+
+  it('short SHA is computed with git rev-parse, not $GITEA_SHA (which is empty)', () => {
+    // Regression: ${GITEA_SHA::7} expands to "" on Gitea runners — nav showed "dev-".
+    // git rev-parse --short HEAD works regardless of which env vars the runner sets.
+    expect(ciYml).toContain('git rev-parse --short HEAD')
+    expect(ciYml).not.toContain('GITEA_SHA')
+  })
 })