diff --git a/umu/umu_run.py b/umu/umu_run.py
index 5405cd929..afe4d16a0 100755
--- a/umu/umu_run.py
+++ b/umu/umu_run.py
@@ -603,16 +603,20 @@ def monitor_windows(
 
     while True:
         # Check if the window sequence has changed
-        current_window_list: set[str] = set(get_window_client_ids(d_secondary))
+        current_window_list: list[str] = get_window_client_ids(d_secondary)
 
         if not current_window_list:
             continue
 
-        if diff := window_client_set.symmetric_difference(current_window_list):
+        if diff := window_client_set.symmetric_difference(
+            set(current_window_list)
+        ):
             log.debug("New windows detected")
             log.debug("current_windows_list: %s", current_window_list)
             log.debug("window_client_set: %s", window_client_set)
             log.debug("difference: %s", diff)
+            window_client_set |= diff
+            log.debug("updated window_client_set: %s", window_client_set)
             set_steam_game_property(d_secondary, diff, steam_assigned_layer_id)
             d_secondary.flush()