diff --git a/src/content/firmwares/elektron-machinedrum/sm.yaml b/src/content/firmwares/elektron-machinedrum/sm.yaml
index 7b0bac5..7fe6c02 100644
--- a/src/content/firmwares/elektron-machinedrum/sm.yaml
+++ b/src/content/firmwares/elektron-machinedrum/sm.yaml
@@ -1,3 +1,4 @@
+# Test PR for the media check: do not merge.
 device: elektron-machinedrum
 name: SM
 kind: tool
@@ -22,7 +23,7 @@ install_notes: >-
 brick_risk: false
 tags: [sample-transfer, sampler, web-midi, sysex, midi, web, librarian]
 image:
-  url: https://sm.fyris.me/og-image.png
+  url: https://httpbin.org/status/404
   alt: SM sample manager with a waveform and two red loop markers, a grid of 48 numbered sample slots with names such as BD01 and LEAD, and slot 22 selected with load, delete, syx and wav buttons
   credit: Fyris
   source_url: https://sm.fyris.me/
diff --git a/wrangler.jsonc b/wrangler.jsonc
index af3576f..266c519 100644
--- a/wrangler.jsonc
+++ b/wrangler.jsonc
@@ -10,5 +10,8 @@
     // Astro's trailingSlash: 'never' and the canonical URLs it emits.
     "html_handling": "drop-trailing-slash"
   },
-  "routes": [{ "pattern": "altstrument.org", "custom_domain": true }]
+  "routes": [{ "pattern": "altstrument.org", "custom_domain": true }],
+  // Workers Builds runs `wrangler preview` for non-production branches, which
+  // needs this block. Empty: the site has no bindings for previews to override.
+  "previews": {}
 }