diff --git a/osu.Game/Scoring/Legacy/LegacyScoreEncoder.cs b/osu.Game/Scoring/Legacy/LegacyScoreEncoder.cs
index 9460ec680c..14a6495282 100644
--- a/osu.Game/Scoring/Legacy/LegacyScoreEncoder.cs
+++ b/osu.Game/Scoring/Legacy/LegacyScoreEncoder.cs
@@ -5,9 +5,11 @@ using System;
 using System.IO;
 using System.Linq;
 using System.Text;
+using JetBrains.Annotations;
 using osu.Framework.Extensions;
 using osu.Game.Beatmaps;
 using osu.Game.IO.Legacy;
+using osu.Game.Replays.Legacy;
 using osu.Game.Rulesets.Replays.Types;
 using SharpCompress.Compressors.LZMA;
 
@@ -29,12 +31,21 @@ namespace osu.Game.Scoring.Legacy
         private readonly Score score;
         private readonly IBeatmap beatmap;
 
-        public LegacyScoreEncoder(Score score, IBeatmap beatmap)
+        /// <summary>
+        /// Create a new score encoder for a specific score.
+        /// </summary>
+        /// <param name="score">The score to be encoded.</param>
+        /// <param name="beatmap">The beatmap used to convert frames for the score. May be null if the frames are already <see cref="LegacyReplayFrame"/>s.</param>
+        /// <exception cref="ArgumentException"></exception>
+        public LegacyScoreEncoder(Score score, [CanBeNull] IBeatmap beatmap)
         {
             this.score = score;
             this.beatmap = beatmap;
 
-            if (score.ScoreInfo.BeatmapInfo.Ruleset.OnlineID < 0 || score.ScoreInfo.BeatmapInfo.Ruleset.OnlineID > 3)
+            if (beatmap == null && !score.Replay.Frames.All(f => f is LegacyReplayFrame))
+                throw new ArgumentException("Beatmap must be provided if frames are not already legacy frames.", nameof(beatmap));
+
+            if (score.ScoreInfo.Ruleset.OnlineID < 0 || score.ScoreInfo.Ruleset.OnlineID > 3)
                 throw new ArgumentException("Only scores in the osu, taiko, catch, or mania rulesets can be encoded to the legacy score format.", nameof(score));
         }