diff --git a/sway/sway-transparency.py b/sway/sway-transparency.py
index 421b53f..8d57777 100755
--- a/sway/sway-transparency.py
+++ b/sway/sway-transparency.py
@@ -20,7 +20,8 @@ def on_window_focus(opacity, ipc, event):
     global prev_focused
     global prev_workspace
     # Refresh previous window in case it changed while in focus
-    prev_focused = ipc.get_tree().find_by_id(prev_focused.id)
+    if prev_focused:
+        prev_focused = ipc.get_tree().find_by_id(prev_focused.id)
 
     focused_workspace = ipc.get_tree().find_focused()
 
@@ -30,9 +31,9 @@ def on_window_focus(opacity, ipc, event):
     focused = event.container
     workspace = focused_workspace.workspace().num
 
-    if prev_focused and focused.id != prev_focused.id:  # https://github.com/swaywm/sway/issues/2859
+    if prev_focused == None or focused.id != prev_focused.id:  # https://github.com/swaywm/sway/issues/2859
         focused.command("opacity 1")
-        if workspace == prev_workspace and not prev_focused.sticky:
+        if prev_focused and workspace == prev_workspace and not prev_focused.sticky:
             prev_focused.command("opacity " + opacity)
         prev_focused = focused
         prev_workspace = workspace