diff --git a/.github/workflows/deploy.yml b/.github/workflows/deploy.yml
index e59402897..70ac7c581 100644
--- a/.github/workflows/deploy.yml
+++ b/.github/workflows/deploy.yml
@@ -65,11 +65,12 @@ jobs:
           SERVER_HOST_US: ${{ secrets.SERVER_HOST_US }}
           SSH_PRIVATE_KEY: ${{ secrets.SSH_PRIVATE_KEY }}
         run: |
+          set -euxo pipefail
           mkdir -p ~/.ssh
           echo "${SSH_PRIVATE_KEY}" > ~/.ssh/id_rsa
-          ssh-keyscan -H "$SERVER_HOST_STAGING" >> ~/.ssh/known_hosts
-          ssh-keyscan -H "$SERVER_HOST_US" >> ~/.ssh/known_hosts
-          ssh-keyscan -H "$SERVER_HOST_EU" >> ~/.ssh/known_hosts
+          test -n "$SERVER_HOST_STAGING" && ssh-keyscan -H "$SERVER_HOST_STAGING" >> ~/.ssh/known_hosts
+          test -n "$SERVER_HOST_US" && ssh-keyscan -H "$SERVER_HOST_US" >> ~/.ssh/known_hosts
+          test -n "$SERVER_HOST_EU" && ssh-keyscan -H "$SERVER_HOST_EU" >> ~/.ssh/known_hosts
           chmod 600 ~/.ssh/id_rsa
       - name: Deploy
         env: