diff --git a/src/calibre/srv/http_response.py b/src/calibre/srv/http_response.py
index 8d9f9112c6..aab51e0304 100644
--- a/src/calibre/srv/http_response.py
+++ b/src/calibre/srv/http_response.py
@@ -341,6 +341,7 @@ class HTTPConnection(HTTPRequest):
                 raise IOError('sendfile() failed to write any bytes to the socket')
         else:
             sent = self.send(buf.read(min(limit, self.send_bufsize)))
+            self.last_activity = monotonic()
         buf.seek(pos + sent)
         return buf.tell() == end