diff --git a/osu.Game/Beatmaps/BeatmapManager.cs b/osu.Game/Beatmaps/BeatmapManager.cs
index 860c7fc0fa..ab08d35f52 100644
--- a/osu.Game/Beatmaps/BeatmapManager.cs
+++ b/osu.Game/Beatmaps/BeatmapManager.cs
@@ -176,20 +176,23 @@ namespace osu.Game.Beatmaps
             if (beatmapInfo?.BeatmapSet == null || beatmapInfo == DefaultBeatmap?.BeatmapInfo)
                 return DefaultBeatmap;
 
-            var cached = workingCache.FirstOrDefault(w => w.BeatmapInfo?.ID == beatmapInfo.ID);
+            lock (workingCache)
+            {
+                var cached = workingCache.FirstOrDefault(w => w.BeatmapInfo?.ID == beatmapInfo.ID);
 
-            if (cached != null)
-                return cached;
+                if (cached != null)
+                    return cached;
 
-            if (beatmapInfo.Metadata == null)
-                beatmapInfo.Metadata = beatmapInfo.BeatmapSet.Metadata;
+                if (beatmapInfo.Metadata == null)
+                    beatmapInfo.Metadata = beatmapInfo.BeatmapSet.Metadata;
 
-            WorkingBeatmap working = new BeatmapManagerWorkingBeatmap(Files.Store, new LargeTextureStore(host?.CreateTextureLoaderStore(Files.Store)), beatmapInfo, audioManager);
+                WorkingBeatmap working = new BeatmapManagerWorkingBeatmap(Files.Store, new LargeTextureStore(host?.CreateTextureLoaderStore(Files.Store)), beatmapInfo, audioManager);
 
-            previous?.TransferTo(working);
-            workingCache.Add(working);
+                previous?.TransferTo(working);
+                workingCache.Add(working);
 
-            return working;
+                return working;
+            }
         }
 
         /// <summary>