diff --git a/.github/workflows/deploy-cors-proxy.yml b/.github/workflows/deploy-cors-proxy.yml
index d0934d1679..c9bd55f56e 100644
--- a/.github/workflows/deploy-cors-proxy.yml
+++ b/.github/workflows/deploy-cors-proxy.yml
@@ -44,7 +44,7 @@ jobs:
             - name: Deploy to CORS proxy server
               shell: bash
               env:
-                  CUSTOM_SUPPORTED_ORIGINS_SPACE_SEPARATED: ${{ secrets.CUSTOM_SUPPORTED_ORIGINS_SPACE_SEPARATED }}
+                  CUSTOM_SUPPORTED_ORIGINS_SPACE_SEPARATED: ${{ vars.CUSTOM_SUPPORTED_ORIGINS_SPACE_SEPARATED }}
               run: |
                   mkdir -p ~/.ssh
                   echo "${{ secrets.DEPLOY_CORS_PROXY_TARGET_HOST_KEY }}" >> ~/.ssh/known_hosts
@@ -73,13 +73,15 @@ jobs:
                     CUSTOM_ORIGINS_PHP="<?php define('PLAYGROUND_CORS_PROXY_SUPPORTED_ORIGINS', array("
 
                     for origin in $CUSTOM_SUPPORTED_ORIGINS_SPACE_SEPARATED; do
+                      # NOTE: These patterns are not perfect but should be sufficient here.
                       if ! (
-                        [[ $origin =~ ^https?://([a-zA-Z0-9-]+\.)*[a-zA-Z]{2,}$ ]] ||
-                        [[ $origin =~ ^https?://([0-9]{1,3}\.){3}[0-9]{1,3}$ ]] ||
-                        [[ $origin =~ ^https?://^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}$ ]]
+                        [[ $origin =~ ^https?:\/\/([a-zA-Z0-9-]+\.)*[a-zA-Z]{2,}(:[[:digit:]]{1,5})?$ ]] ||
+                        [[ $origin =~ ^https?://([0-9]{1,3}\.){3}[0-9]{1,3}(:[[:digit:]]{1,5})?$ ]] ||
+                        [[ $origin =~ ^https?://^([0-9a-fA-F]{1,4}:){7}[0-9a-fA-F]{1,4}(:[[:digit:]]{1,5})?$ ]]
                       ); then
                         echo "Unable to use CUSTOM_SUPPORTED_ORIGINS_SPACE_SEPARATED"
                         echo "Invalid origin: '$origin'"
+                        echo "Full contents: '${CUSTOM_SUPPORTED_ORIGINS_SPACE_SEPARATED}'"
                         exit -1;
                       fi