diff --git a/app.py b/app.py
index 2c14299..0dee807 100755
--- a/app.py
+++ b/app.py
@@ -799,6 +799,16 @@ def serve_file(subpath):
     else:
         cache = cache_other
 
+    # Plain HEAD requests (without X-Cache-Request) should not populate the cache.
+    # They are just probes and would otherwise turn the first real GET into a “cached hit”.
+    if request.method == 'HEAD' and not is_cache_request:
+        response = make_response('', 200)
+        response.headers['Content-Type'] = mime
+        response.headers['Content-Length'] = str(filesize)
+        response.headers['Accept-Ranges'] = 'bytes'
+        response.headers['Cache-Control'] = 'public, max-age=86400'
+        return response
+
     # 4) Image and thumbnail handling first
     if mime.startswith('image/'):
         small = request.args.get('thumbnail') == 'true'