diff --git a/osu.Desktop.VisualTests/Tests/TestCasePlayer.cs b/osu.Desktop.VisualTests/Tests/TestCasePlayer.cs
index ee58d934a4..0b876ed171 100644
--- a/osu.Desktop.VisualTests/Tests/TestCasePlayer.cs
+++ b/osu.Desktop.VisualTests/Tests/TestCasePlayer.cs
@@ -110,7 +110,7 @@ namespace osu.Desktop.VisualTests.Tests
                 Beatmap = beatmap;
             }
 
-            protected override ArchiveReader GetReader() => null;
+            protected override BeatmapArchiveReader GetReader() => null;
         }
     }
 }
diff --git a/osu.Desktop/Beatmaps/IO/LegacyFilesystemReader.cs b/osu.Desktop/Beatmaps/IO/LegacyFilesystemReader.cs
index 0ef448cafe..19aa9ca4a6 100644
--- a/osu.Desktop/Beatmaps/IO/LegacyFilesystemReader.cs
+++ b/osu.Desktop/Beatmaps/IO/LegacyFilesystemReader.cs
@@ -13,7 +13,7 @@ namespace osu.Desktop.Beatmaps.IO
     /// <summary>
     /// Reads an extracted legacy beatmap from disk.
     /// </summary>
-    public class LegacyFilesystemReader : ArchiveReader
+    public class LegacyFilesystemReader : BeatmapArchiveReader
     {
         public static void Register() => AddReader<LegacyFilesystemReader>((storage, path) => Directory.Exists(path));
 
diff --git a/osu.Desktop/OsuGameDesktop.cs b/osu.Desktop/OsuGameDesktop.cs
index 3b827f2809..a09f9860cb 100644
--- a/osu.Desktop/OsuGameDesktop.cs
+++ b/osu.Desktop/OsuGameDesktop.cs
@@ -12,6 +12,7 @@ using System.Drawing;
 using System.IO;
 using System.Threading.Tasks;
 using osu.Game.Screens.Menu;
+using osu.Game.Beatmaps.IO;
 
 namespace osu.Desktop
 {
@@ -57,7 +58,7 @@ namespace osu.Desktop
             var dropData = (object[])e.Data.GetData(DataFormats.FileDrop);
             var filePaths = dropData.Select(f => f.ToString()).ToArray();
 
-            if (filePaths.All(f => Path.GetExtension(f) == @".osz"))
+            if (filePaths.All(f => Path.GetExtension(f) == BeatmapArchiveReader.OSZ_EXTENSION))
                 Task.Run(() => BeatmapDatabase.Import(filePaths));
             else if (filePaths.All(f => Path.GetExtension(f) == @".osr"))
                 Task.Run(() =>
@@ -67,7 +68,7 @@ namespace osu.Desktop
                 });
         }
 
-        private static readonly string[] allowed_extensions = { @".osz", @".osr" };
+        private static readonly string[] allowed_extensions = { BeatmapArchiveReader.OSZ_EXTENSION, @".osr" };
 
         private void dragEnter(DragEventArgs e)
         {
diff --git a/osu.Game.Tests/Beatmaps/IO/ImportBeatmapTest.cs b/osu.Game.Tests/Beatmaps/IO/ImportBeatmapTest.cs
index ae936f3f49..a6ab6a989b 100644
--- a/osu.Game.Tests/Beatmaps/IO/ImportBeatmapTest.cs
+++ b/osu.Game.Tests/Beatmaps/IO/ImportBeatmapTest.cs
@@ -17,6 +17,7 @@ using osu.Game.Modes.Catch;
 using osu.Game.Modes.Mania;
 using osu.Game.Modes.Osu;
 using osu.Game.Modes.Taiko;
+using osu.Game.Beatmaps.IO;
 
 namespace osu.Game.Tests.Beatmaps.IO
 {
@@ -106,7 +107,7 @@ namespace osu.Game.Tests.Beatmaps.IO
 
         private string prepareTempCopy(string path)
         {
-            var temp = Path.GetTempFileName();
+            var temp = Path.GetTempPath() + Guid.NewGuid() + BeatmapArchiveReader.OSZ_EXTENSION;
             return new FileInfo(path).CopyTo(temp, true).FullName;
         }
 
diff --git a/osu.Game/Beatmaps/IO/BeatmapArchiveReader.cs b/osu.Game/Beatmaps/IO/BeatmapArchiveReader.cs
new file mode 100644
index 0000000000..0fab05df49
--- /dev/null
+++ b/osu.Game/Beatmaps/IO/BeatmapArchiveReader.cs
@@ -0,0 +1,44 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using System;
+using osu.Framework.Logging;
+using osu.Framework.Platform;
+using osu.Game.Database;
+using osu.Game.IO;
+
+namespace osu.Game.Beatmaps.IO
+{
+    public abstract class BeatmapArchiveReader : ArchiveReader
+    {
+        public const string OSZ_EXTENSION = @".osz";
+
+        public static BeatmapArchiveReader GetBeatmapArchiveReader(Storage storage, string path)
+        {
+            try
+            {
+                return (BeatmapArchiveReader)GetReader(storage, path);
+            }
+            catch (InvalidCastException e)
+            {
+                Logger.Error(e, "A tricky  " + $@"{nameof(ArchiveReader)}" + " instance passed the test to be a " + $@"{nameof(BeatmapArchiveReader)}" + ", but it's really not");
+                throw;
+            }
+        }
+
+        /// <summary>
+        /// Reads the beatmap metadata from this archive.
+        /// </summary>
+        public abstract BeatmapMetadata ReadMetadata();
+
+        /// <summary>
+        /// Gets a list of beatmap file names.
+        /// </summary>
+        public string[] BeatmapFilenames { get; protected set; }
+
+        /// <summary>
+        /// The storyboard filename. Null if no storyboard is present.
+        /// </summary>
+        public string StoryboardFilename { get; protected set; }
+    }
+}
\ No newline at end of file
diff --git a/osu.Game/Beatmaps/IO/OszArchiveReader.cs b/osu.Game/Beatmaps/IO/OszArchiveReader.cs
index 8a1d071cfc..8c3e4d702c 100644
--- a/osu.Game/Beatmaps/IO/OszArchiveReader.cs
+++ b/osu.Game/Beatmaps/IO/OszArchiveReader.cs
@@ -9,14 +9,14 @@ using osu.Game.Database;
 
 namespace osu.Game.Beatmaps.IO
 {
-    public sealed class OszArchiveReader : ArchiveReader
+    public sealed class OszArchiveReader : BeatmapArchiveReader
     {
         public static void Register()
         {
             AddReader<OszArchiveReader>((storage, path) =>
             {
                 using (var stream = storage.GetStream(path))
-                    return ZipFile.IsZipFile(stream, false);
+                    return Path.GetExtension(path) == OSZ_EXTENSION && ZipFile.IsZipFile(stream, false);
             });
             OsuLegacyDecoder.Register();
         }
diff --git a/osu.Game/Beatmaps/WorkingBeatmap.cs b/osu.Game/Beatmaps/WorkingBeatmap.cs
index 16db4fc2a6..cf3f982082 100644
--- a/osu.Game/Beatmaps/WorkingBeatmap.cs
+++ b/osu.Game/Beatmaps/WorkingBeatmap.cs
@@ -33,7 +33,7 @@ namespace osu.Game.Beatmaps
 
         public readonly bool WithStoryboard;
 
-        protected abstract ArchiveReader GetReader();
+        protected abstract BeatmapArchiveReader GetReader();
 
         protected WorkingBeatmap(BeatmapInfo beatmapInfo, BeatmapSetInfo beatmapSetInfo, bool withStoryboard = false)
         {
@@ -101,7 +101,7 @@ namespace osu.Game.Beatmaps
             set { lock (beatmapLock) beatmap = value; }
         }
 
-        private ArchiveReader trackReader;
+        private BeatmapArchiveReader trackReader;
         private Track track;
         private object trackLock = new object();
         public Track Track
diff --git a/osu.Game/Database/BeatmapDatabase.cs b/osu.Game/Database/BeatmapDatabase.cs
index 871251b882..a9fe30a5e9 100644
--- a/osu.Game/Database/BeatmapDatabase.cs
+++ b/osu.Game/Database/BeatmapDatabase.cs
@@ -177,7 +177,7 @@ namespace osu.Game.Database
 
             BeatmapMetadata metadata;
 
-            using (var reader = ArchiveReader.GetReader(storage, path))
+            using (var reader = BeatmapArchiveReader.GetBeatmapArchiveReader(storage, path))
                 metadata = reader.ReadMetadata();
 
             if (File.Exists(path)) // Not always the case, i.e. for LegacyFilesystemReader
@@ -186,7 +186,7 @@ namespace osu.Game.Database
                 {
                     hash = input.GetMd5Hash();
                     input.Seek(0, SeekOrigin.Begin);
-                    path = Path.Combine(@"beatmaps", hash.Remove(1), hash.Remove(2), hash);
+                    path = Path.Combine(@"beatmaps", hash.Remove(1), hash.Remove(2), hash + BeatmapArchiveReader.OSZ_EXTENSION);
                     if (!storage.Exists(path))
                         using (var output = storage.GetStream(path, FileAccess.Write))
                             input.CopyTo(output);
@@ -216,7 +216,7 @@ namespace osu.Game.Database
                 Metadata = metadata
             };
 
-            using (var archive = ArchiveReader.GetReader(storage, path))
+            using (var archive = BeatmapArchiveReader.GetBeatmapArchiveReader(storage, path))
             {
                 string[] mapNames = archive.BeatmapFilenames;
                 foreach (var name in mapNames)
@@ -268,12 +268,12 @@ namespace osu.Game.Database
             BeatmapSetRemoved?.Invoke(beatmapSet);
         }
 
-        public ArchiveReader GetReader(BeatmapSetInfo beatmapSet)
+        public BeatmapArchiveReader GetReader(BeatmapSetInfo beatmapSet)
         {
             if (string.IsNullOrEmpty(beatmapSet.Path))
                 return null;
 
-            return ArchiveReader.GetReader(storage, beatmapSet.Path);
+            return BeatmapArchiveReader.GetBeatmapArchiveReader(storage, beatmapSet.Path);
         }
 
         public BeatmapSetInfo GetBeatmapSet(int id)
@@ -354,7 +354,7 @@ namespace osu.Game.Database
                 this.database = database;
             }
 
-            protected override ArchiveReader GetReader() => database?.GetReader(BeatmapSetInfo);
+            protected override BeatmapArchiveReader GetReader() => database?.GetReader(BeatmapSetInfo);
         }
     }
 }
diff --git a/osu.Game/Beatmaps/IO/ArchiveReader.cs b/osu.Game/IO/ArchiveReader.cs
similarity index 65%
rename from osu.Game/Beatmaps/IO/ArchiveReader.cs
rename to osu.Game/IO/ArchiveReader.cs
index bbf4de20f5..8eaecdeabc 100644
--- a/osu.Game/Beatmaps/IO/ArchiveReader.cs
+++ b/osu.Game/IO/ArchiveReader.cs
@@ -6,23 +6,22 @@ using System.Collections.Generic;
 using System.IO;
 using osu.Framework.IO.Stores;
 using osu.Framework.Platform;
-using osu.Game.Database;
 
-namespace osu.Game.Beatmaps.IO
+namespace osu.Game.IO
 {
     public abstract class ArchiveReader : IDisposable, IResourceStore<byte[]>
     {
-        private class Reader
+        protected class Reader
         {
             public Func<Storage, string, bool> Test { get; set; }
             public Type Type { get; set; }
         }
 
-        private static List<Reader> readers { get; } = new List<Reader>();
+        protected static List<Reader> Readers { get; } = new List<Reader>();
 
         public static ArchiveReader GetReader(Storage storage, string path)
         {
-            foreach (var reader in readers)
+            foreach (var reader in Readers)
             {
                 if (reader.Test(storage, path))
                     return (ArchiveReader)Activator.CreateInstance(reader.Type, storage.GetStream(path));
@@ -32,24 +31,9 @@ namespace osu.Game.Beatmaps.IO
 
         protected static void AddReader<T>(Func<Storage, string, bool> test) where T : ArchiveReader
         {
-            readers.Add(new Reader { Test = test, Type = typeof(T) });
+            Readers.Add(new Reader { Test = test, Type = typeof(T) });
         }
 
-        /// <summary>
-        /// Reads the beatmap metadata from this archive.
-        /// </summary>
-        public abstract BeatmapMetadata ReadMetadata();
-
-        /// <summary>
-        /// Gets a list of beatmap file names.
-        /// </summary>
-        public string[] BeatmapFilenames { get; protected set; }
-
-        /// <summary>
-        /// The storyboard filename. Null if no storyboard is present.
-        /// </summary>
-        public string StoryboardFilename { get; protected set; }
-
         /// <summary>
         /// Opens a stream for reading a specific file from this archive.
         /// </summary>
diff --git a/osu.Game/osu.Game.csproj b/osu.Game/osu.Game.csproj
index 46cb593d20..e13e8b6b2f 100644
--- a/osu.Game/osu.Game.csproj
+++ b/osu.Game/osu.Game.csproj
@@ -241,7 +241,7 @@
     <Compile Include="Users\User.cs" />
     <Compile Include="Graphics\UserInterface\Volume\VolumeControl.cs" />
     <Compile Include="Database\BeatmapDatabase.cs" />
-    <Compile Include="Beatmaps\IO\ArchiveReader.cs" />
+    <Compile Include="Beatmaps\IO\BeatmapArchiveReader.cs" />
     <Compile Include="Beatmaps\Formats\BeatmapDecoder.cs" />
     <Compile Include="Beatmaps\Formats\OsuLegacyDecoder.cs" />
     <Compile Include="Beatmaps\IO\OszArchiveReader.cs" />
@@ -329,6 +329,7 @@
     <Compile Include="Screens\Select\Options\BeatmapOptionsEditButton.cs" />
     <Compile Include="Screens\Select\Options\BeatmapOptionsOverlay.cs" />
     <Compile Include="Screens\Select\Options\BeatmapOptionsRemoveFromUnplayedButton.cs" />
+    <Compile Include="IO\ArchiveReader.cs" />
   </ItemGroup>
   <ItemGroup>
     <ProjectReference Include="$(SolutionDir)\osu-framework\osu.Framework\osu.Framework.csproj">