diff --git a/osu.Game.Rulesets.Mania/Beatmaps/ManiaBeatmapConverter.cs b/osu.Game.Rulesets.Mania/Beatmaps/ManiaBeatmapConverter.cs
index f6d30ad3fa..d5a799b4ed 100644
--- a/osu.Game.Rulesets.Mania/Beatmaps/ManiaBeatmapConverter.cs
+++ b/osu.Game.Rulesets.Mania/Beatmaps/ManiaBeatmapConverter.cs
@@ -138,8 +138,8 @@ namespace osu.Game.Rulesets.Mania.Beatmaps
             Pattern newPattern = conversion.Generate();
             lastPattern = newPattern;
 
-            var stairPatternGenerator = (HitObjectPatternGenerator)conversion;
-            lastStair = stairPatternGenerator.StairType;
+            var stairPatternGenerator = conversion as HitObjectPatternGenerator;
+            lastStair = stairPatternGenerator?.StairType ?? lastStair;
 
             return newPattern.HitObjects;
         }