diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 60b7276..e64080b 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -61,14 +61,16 @@ jobs:
           apiToken: ${{ secrets.CLOUDFLARE_API_TOKEN_WORKERS }}
           command: "deploy --minify src/index.ts --env ${{ env.MODE }}"
           workingDirectory: ./api
-          secrets: |
-            MODE
-            API_MAIL_DKIM_PRIVATE_KEY
-            API_DISCORD_WEBHOOK_URL_CONTACT
-            API_DISCORD_WEBHOOK_MENTION_ID
-            API_CONTACT_MANIFEST
-            API_ASSETS_ENDPOINT
-            API_ASSETS_ACCESS_KEY
+          # `secrets` プロパティーを指定するやり方だと, Workers はちゃんと env に従ってデプロイされるけど,
+          # Secrets はなぜか env を無視して put してしまうのでここで自前で put する.
+          postCommands: |
+            wrangler secret put MODE --env ${{ env.MODE }}
+            wrangler secret put API_MAIL_DKIM_PRIVATE_KEY --env ${{ env.MODE }}
+            wrangler secret put API_DISCORD_WEBHOOK_URL_CONTACT --env ${{ env.MODE }}
+            wrangler secret put API_DISCORD_WEBHOOK_MENTION_ID --env ${{ env.MODE }}
+            wrangler secret put API_CONTACT_MANIFEST --env ${{ env.MODE }}
+            wrangler secret put API_ASSETS_ENDPOINT --env ${{ env.MODE }}
+            wrangler secret put API_ASSETS_ACCESS_KEY --env ${{ env.MODE }}
         env:
           MODE: ${{ env.MODE }}
           API_MAIL_DKIM_PRIVATE_KEY: ${{ secrets.API_MAIL_DKIM_PRIVATE_KEY }}