diff --git a/.github/workflows/deploy_fastapi_backend.yml b/.github/workflows/deploy_fastapi_backend.yml
index 60f2527c..0b2769dc 100644
--- a/.github/workflows/deploy_fastapi_backend.yml
+++ b/.github/workflows/deploy_fastapi_backend.yml
@@ -44,6 +44,10 @@ jobs:
           aws-secret-access-key: ${{ secrets.PROD_AWS_SECRET_ACCESS_KEY }}
           aws-region: eu-west-2
 
+      - name: Set domain name
+        id: set_domain
+        run: echo "::set-output name=domain::${{ secrets[format('{0}_DOMAIN_NAME', github.ref_name)] }}"
+
       - name: Deploy to AWS Lambda via Serverless
         env:
           API_KEY: ${{ secrets.FASTAPI_API_KEY }}
@@ -51,5 +55,5 @@ jobs:
           SECRET_KEY: ${{ secrets.NEXTAUTH_SECRET }}
           ALGORITHM: 'HS256'
           PLAN_TRIGGER_BUCKET: 'retrofit-plan-inputs-${{ github.ref_name }}'
-          DOMAIN_NAME: "${{ github.ref_name }}_DOMAIN_NAME"
+          DOMAIN_NAME: ${{ steps.set_domain.outputs.domain }}
         run: cd backend && sls deploy --stage ${{ github.ref_name }} --verbose