diff --git a/run.py b/run.py
index a8bd2baf..fbcd001e 100644
--- a/run.py
+++ b/run.py
@@ -1,6 +1,11 @@
 import sys
+import os
 import faulthandler
 
+# OCP's Xw_Window requires an X11 window ID, so we force XCB so winId() is valid under Wayland/XWayland.
+if sys.platform == "linux" and "QT_QPA_PLATFORM" not in os.environ:
+    os.environ["QT_QPA_PLATFORM"] = "xcb"
+
 # PyInstaller with console=False sets sys.stdout/stderr to None on Windows
 if sys.stdout is None:
     sys.stdout = open("nul", "w")