diff --git a/osu.Game/Input/IdleTracker.cs b/osu.Game/Input/IdleTracker.cs
index 4ef676b3b6..e2f13309cf 100644
--- a/osu.Game/Input/IdleTracker.cs
+++ b/osu.Game/Input/IdleTracker.cs
@@ -70,6 +70,9 @@ namespace osu.Game.Input
 
         protected override bool Handle(UIEvent e)
         {
+            // Even when not active, `MouseMoveEvent`s will arrive.
+            // We don't want these to trigger a non-idle state as it's quite often the user interacting
+            // with other windows while osu! is in the background.
             if (!host.IsActive.Value)
                 return base.Handle(e);