diff --git a/docker/nginx.conf b/docker/nginx.conf
index 54699d93..f02a7bc2 100644
--- a/docker/nginx.conf
+++ b/docker/nginx.conf
@@ -11,8 +11,11 @@ server {
         try_files $uri $uri/ /index.html;
     }
 
+    # Filenames here aren't content-hashed, so a long/immutable cache would keep
+    # serving a stale bundle after every deploy. Force revalidation instead:
+    # cheap 304s when unchanged, immediate pickup of new content when not.
     location /umd/ {
-        add_header Cache-Control "public, max-age=31536000, immutable";
+        add_header Cache-Control "no-cache";
     }
 
     location /img/ {