diff --git a/osu.Game/Beatmaps/BeatmapDifficultyCache.cs b/osu.Game/Beatmaps/BeatmapDifficultyCache.cs
index 3ca0b47121..be278622b5 100644
--- a/osu.Game/Beatmaps/BeatmapDifficultyCache.cs
+++ b/osu.Game/Beatmaps/BeatmapDifficultyCache.cs
@@ -2,7 +2,6 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.Linq;