diff --git a/.github/workflows/purge-readme-image-cache.yml b/.github/workflows/purge-readme-image-cache.yml
index c9e2358..7e72136 100644
--- a/.github/workflows/purge-readme-image-cache.yml
+++ b/.github/workflows/purge-readme-image-cache.yml
@@ -2,7 +2,7 @@ name: Purge image cache
 
 on:
   schedule:
-    - cron: '4 18 * * *'
+    - cron: '4 18 * * */7'
 
 jobs:
   purge: