diff --git a/osu.Game/Storyboards/SpriteDefinition.cs b/osu.Game/Storyboards/SpriteDefinition.cs
index c1a3588960..4f161a34f4 100644
--- a/osu.Game/Storyboards/SpriteDefinition.cs
+++ b/osu.Game/Storyboards/SpriteDefinition.cs
@@ -19,8 +19,8 @@ namespace osu.Game.Storyboards
         private readonly List<CommandLoop> loops = new List<CommandLoop>();
         private readonly List<CommandTrigger> triggers = new List<CommandTrigger>();
 
-        private delegate void DrawablePropertyInitializer<T>(Drawable drawable, T value);
-        private delegate void DrawableTransformer<T>(Drawable drawable, T value, double duration, Easing easing);
+        private delegate void DrawablePropertyInitializer<in T>(Drawable drawable, T value);
+        private delegate void DrawableTransformer<in T>(Drawable drawable, T value, double duration, Easing easing);
 
         public SpriteDefinition(string path, Anchor origin, Vector2 initialPosition)
         {
diff --git a/osu.Game/Storyboards/StoryboardDefinition.cs b/osu.Game/Storyboards/StoryboardDefinition.cs
index e357440bc9..4ef24cda91 100644
--- a/osu.Game/Storyboards/StoryboardDefinition.cs
+++ b/osu.Game/Storyboards/StoryboardDefinition.cs
@@ -9,7 +9,7 @@ namespace osu.Game.Storyboards
 {
     public class StoryboardDefinition
     {
-        private Dictionary<string, LayerDefinition> layers = new Dictionary<string, LayerDefinition>();
+        private readonly Dictionary<string, LayerDefinition> layers = new Dictionary<string, LayerDefinition>();
         public IEnumerable<LayerDefinition> Layers => layers.Values;
 
         public StoryboardDefinition()