diff --git a/html5/js/Client.js b/html5/js/Client.js
index 97940ebf..63006cc9 100644
--- a/html5/js/Client.js
+++ b/html5/js/Client.js
@@ -544,6 +544,9 @@ class XpraClient {
       return;
     }
     this.offscreen_api = DECODE_WORKER && XpraOffscreenWorker.isAvailable(this.ssl);
+    if (this.offscreen_api) {
+      self.set_encoding_option('video_max_size',[4096, 4096]);
+    }
     this.clog("we have webworker support");
     // spawn worker that checks for a websocket
     const worker = new Worker("js/lib/wsworker_check.js");