diff --git a/osu.Game/Skinning/ISkin.cs b/osu.Game/Skinning/ISkin.cs
index 73f7cf6d39..414a316dec 100644
--- a/osu.Game/Skinning/ISkin.cs
+++ b/osu.Game/Skinning/ISkin.cs
@@ -1,7 +1,8 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-using JetBrains.Annotations;
+#nullable enable
+
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
 using osu.Framework.Graphics;
@@ -21,16 +22,14 @@ namespace osu.Game.Skinning
         /// </summary>
         /// <param name="component">The requested component.</param>
         /// <returns>A drawable representation for the requested component, or null if unavailable.</returns>
-        [CanBeNull]
-        Drawable GetDrawableComponent(ISkinComponent component);
+        Drawable? GetDrawableComponent(ISkinComponent component);
 
         /// <summary>
         /// Retrieve a <see cref="Texture"/>.
         /// </summary>
         /// <param name="componentName">The requested texture.</param>
         /// <returns>A matching texture, or null if unavailable.</returns>
-        [CanBeNull]
-        Texture GetTexture(string componentName) => GetTexture(componentName, default, default);
+        Texture? GetTexture(string componentName) => GetTexture(componentName, default, default);
 
         /// <summary>
         /// Retrieve a <see cref="Texture"/>.
@@ -39,23 +38,22 @@ namespace osu.Game.Skinning
         /// <param name="wrapModeS">The texture wrap mode in horizontal direction.</param>
         /// <param name="wrapModeT">The texture wrap mode in vertical direction.</param>
         /// <returns>A matching texture, or null if unavailable.</returns>
-        [CanBeNull]
-        Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
+        Texture? GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
 
         /// <summary>
         /// Retrieve a <see cref="SampleChannel"/>.
         /// </summary>
         /// <param name="sampleInfo">The requested sample.</param>
         /// <returns>A matching sample channel, or null if unavailable.</returns>
-        [CanBeNull]
-        ISample GetSample(ISampleInfo sampleInfo);
+        ISample? GetSample(ISampleInfo sampleInfo);
 
         /// <summary>
         /// Retrieve a configuration value.
         /// </summary>
         /// <param name="lookup">The requested configuration value.</param>
         /// <returns>A matching value boxed in an <see cref="IBindable{TValue}"/>, or null if unavailable.</returns>
-        [CanBeNull]
-        IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup);
+        IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
+            where TLookup : notnull
+            where TValue : notnull;
     }
 }
diff --git a/osu.Game/Skinning/LegacyBeatmapSkin.cs b/osu.Game/Skinning/LegacyBeatmapSkin.cs
index e3685c986b..16a05f4197 100644
--- a/osu.Game/Skinning/LegacyBeatmapSkin.cs
+++ b/osu.Game/Skinning/LegacyBeatmapSkin.cs
@@ -1,9 +1,11 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
-using JetBrains.Annotations;
+#nullable enable
+
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
+using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics;
 using osu.Framework.IO.Stores;
 using osu.Game.Audio;
@@ -26,14 +28,14 @@ namespace osu.Game.Skinning
         /// </summary>
         /// <param name="beatmapInfo">The model for this beatmap.</param>
         /// <param name="resources">Access to raw game resources.</param>
-        public LegacyBeatmapSkin(BeatmapInfo beatmapInfo, [CanBeNull] IStorageResourceProvider resources)
-            : base(createSkinInfo(beatmapInfo), resources, createRealmBackedStore(beatmapInfo, resources), beatmapInfo.Path)
+        public LegacyBeatmapSkin(BeatmapInfo beatmapInfo, IStorageResourceProvider? resources)
+            : base(createSkinInfo(beatmapInfo), resources, createRealmBackedStore(beatmapInfo, resources), beatmapInfo.Path.AsNonNull())
         {
             // Disallow default colours fallback on beatmap skins to allow using parent skin combo colours. (via SkinProvidingContainer)
             Configuration.AllowDefaultComboColoursFallback = false;
         }
 
-        private static IResourceStore<byte[]> createRealmBackedStore(BeatmapInfo beatmapInfo, [CanBeNull] IStorageResourceProvider resources)
+        private static IResourceStore<byte[]> createRealmBackedStore(BeatmapInfo beatmapInfo, IStorageResourceProvider? resources)
         {
             if (resources == null)
                 // should only ever be used in tests.
@@ -42,7 +44,7 @@ namespace osu.Game.Skinning
             return new RealmBackedResourceStore(beatmapInfo.BeatmapSet, resources.Files, new[] { @"ogg" });
         }
 
-        public override Drawable GetDrawableComponent(ISkinComponent component)
+        public override Drawable? GetDrawableComponent(ISkinComponent component)
         {
             if (component is SkinnableTargetComponent targetComponent)
             {
@@ -61,7 +63,7 @@ namespace osu.Game.Skinning
             return base.GetDrawableComponent(component);
         }
 
-        public override IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup)
+        public override IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
         {
             switch (lookup)
             {
@@ -77,10 +79,10 @@ namespace osu.Game.Skinning
             return base.GetConfig<TLookup, TValue>(lookup);
         }
 
-        protected override IBindable<Color4> GetComboColour(IHasComboColours source, int comboIndex, IHasComboInformation combo)
+        protected override IBindable<Color4>? GetComboColour(IHasComboColours source, int comboIndex, IHasComboInformation combo)
             => base.GetComboColour(source, combo.ComboIndexWithOffsets, combo);
 
-        public override ISample GetSample(ISampleInfo sampleInfo)
+        public override ISample? GetSample(ISampleInfo sampleInfo)
         {
             if (sampleInfo is ConvertHitObjectParser.LegacyHitSampleInfo legacy && legacy.CustomSampleBank == 0)
             {
diff --git a/osu.Game/Skinning/LegacySkin.cs b/osu.Game/Skinning/LegacySkin.cs
index 244774fd4c..92713023f4 100644
--- a/osu.Game/Skinning/LegacySkin.cs
+++ b/osu.Game/Skinning/LegacySkin.cs
@@ -1,6 +1,8 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
 using System.Diagnostics;
@@ -57,7 +59,7 @@ namespace osu.Game.Skinning
         /// <param name="resources">Access to raw game resources.</param>
         /// <param name="storage">An optional store which will be used for looking up skin resources. If null, one will be created from realm <see cref="IHasRealmFiles"/> pattern.</param>
         /// <param name="configurationFilename">The user-facing filename of the configuration file to be parsed. Can accept an .osu or skin.ini file.</param>
-        protected LegacySkin(SkinInfo skin, [CanBeNull] IStorageResourceProvider resources, [CanBeNull] IResourceStore<byte[]> storage, string configurationFilename = @"skin.ini")
+        protected LegacySkin(SkinInfo skin, IStorageResourceProvider? resources, IResourceStore<byte[]>? storage, string configurationFilename = @"skin.ini")
             : base(skin, resources, storage, configurationFilename)
         {
             // todo: this shouldn't really be duplicated here (from ManiaLegacySkinTransformer). we need to come up with a better solution.
@@ -81,7 +83,7 @@ namespace osu.Game.Skinning
             }
         }
 
-        public override IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup)
+        public override IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
         {
             switch (lookup)
             {
@@ -127,7 +129,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        private IBindable<TValue> lookupForMania<TValue>(LegacyManiaSkinConfigurationLookup maniaLookup)
+        private IBindable<TValue>? lookupForMania<TValue>(LegacyManiaSkinConfigurationLookup maniaLookup)
         {
             if (!maniaConfigurations.TryGetValue(maniaLookup.Keys, out var existing))
                 maniaConfigurations[maniaLookup.Keys] = existing = new LegacyManiaSkinConfiguration(maniaLookup.Keys);
@@ -267,20 +269,20 @@ namespace osu.Game.Skinning
         /// <param name="source">The source to retrieve the combo colours from.</param>
         /// <param name="colourIndex">The preferred index for retrieving the combo colour with.</param>
         /// <param name="combo">Information on the combo whose using the returned colour.</param>
-        protected virtual IBindable<Color4> GetComboColour(IHasComboColours source, int colourIndex, IHasComboInformation combo)
+        protected virtual IBindable<Color4>? GetComboColour(IHasComboColours source, int colourIndex, IHasComboInformation combo)
         {
             var colour = source.ComboColours?[colourIndex % source.ComboColours.Count];
             return colour.HasValue ? new Bindable<Color4>(colour.Value) : null;
         }
 
-        private IBindable<Color4> getCustomColour(IHasCustomColours source, string lookup)
+        private IBindable<Color4>? getCustomColour(IHasCustomColours source, string lookup)
             => source.CustomColours.TryGetValue(lookup, out var col) ? new Bindable<Color4>(col) : null;
 
-        private IBindable<string> getManiaImage(LegacyManiaSkinConfiguration source, string lookup)
+        private IBindable<string>? getManiaImage(LegacyManiaSkinConfiguration source, string lookup)
             => source.ImageLookups.TryGetValue(lookup, out string image) ? new Bindable<string>(image) : null;
 
-        [CanBeNull]
-        private IBindable<TValue> legacySettingLookup<TValue>(SkinConfiguration.LegacySetting legacySetting)
+        private IBindable<TValue>? legacySettingLookup<TValue>(SkinConfiguration.LegacySetting legacySetting)
+            where TValue : notnull
         {
             switch (legacySetting)
             {
@@ -292,8 +294,9 @@ namespace osu.Game.Skinning
             }
         }
 
-        [CanBeNull]
-        private IBindable<TValue> genericLookup<TLookup, TValue>(TLookup lookup)
+        private IBindable<TValue>? genericLookup<TLookup, TValue>(TLookup lookup)
+            where TLookup : notnull
+            where TValue : notnull
         {
             try
             {
@@ -316,7 +319,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public override Drawable GetDrawableComponent(ISkinComponent component)
+        public override Drawable? GetDrawableComponent(ISkinComponent component)
         {
             if (base.GetDrawableComponent(component) is Drawable c)
                 return c;
@@ -374,7 +377,7 @@ namespace osu.Game.Skinning
 
                 case GameplaySkinComponent<HitResult> resultComponent:
                     // TODO: this should be inside the judgement pieces.
-                    Func<Drawable> createDrawable = () => getJudgementAnimation(resultComponent.Component);
+                    Func<Drawable?> createDrawable = () => getJudgementAnimation(resultComponent.Component);
 
                     // kind of wasteful that we throw this away, but should do for now.
                     if (createDrawable() != null)
@@ -393,7 +396,7 @@ namespace osu.Game.Skinning
             return this.GetAnimation(component.LookupName, false, false);
         }
 
-        private Texture getParticleTexture(HitResult result)
+        private Texture? getParticleTexture(HitResult result)
         {
             switch (result)
             {
@@ -410,7 +413,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        private Drawable getJudgementAnimation(HitResult result)
+        private Drawable? getJudgementAnimation(HitResult result)
         {
             switch (result)
             {
@@ -430,7 +433,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public override Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT)
+        public override Texture? GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT)
         {
             foreach (string name in getFallbackNames(componentName))
             {
@@ -458,7 +461,7 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public override ISample GetSample(ISampleInfo sampleInfo)
+        public override ISample? GetSample(ISampleInfo sampleInfo)
         {
             IEnumerable<string> lookupNames;
 
diff --git a/osu.Game/Skinning/ResourceStoreBackedSkin.cs b/osu.Game/Skinning/ResourceStoreBackedSkin.cs
index 4787b5a4e9..48286bff59 100644
--- a/osu.Game/Skinning/ResourceStoreBackedSkin.cs
+++ b/osu.Game/Skinning/ResourceStoreBackedSkin.cs
@@ -46,7 +46,10 @@ namespace osu.Game.Skinning
             return null;
         }
 
-        public IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup) => null;
+        public IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
+            where TLookup : notnull
+            where TValue : notnull
+            => null;
 
         public void Dispose()
         {
diff --git a/osu.Game/Skinning/Skin.cs b/osu.Game/Skinning/Skin.cs
index e00dd950a7..324ed90a67 100644
--- a/osu.Game/Skinning/Skin.cs
+++ b/osu.Game/Skinning/Skin.cs
@@ -1,12 +1,14 @@
 // Copyright (c) ppy Pty Ltd <contact@ppy.sh>. Licensed under the MIT Licence.
 // See the LICENCE file in the repository root for full licence text.
 
+#nullable enable
+
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.IO;
 using System.Linq;
 using System.Text;
-using JetBrains.Annotations;
 using Newtonsoft.Json;
 using osu.Framework.Audio.Sample;
 using osu.Framework.Bindables;
@@ -27,14 +29,12 @@ namespace osu.Game.Skinning
         /// <summary>
         /// A texture store which can be used to perform user file lookups for this skin.
         /// </summary>
-        [CanBeNull]
-        protected TextureStore Textures { get; }
+        protected TextureStore? Textures { get; }
 
         /// <summary>
         /// A sample store which can be used to perform user file lookups for this skin.
         /// </summary>
-        [CanBeNull]
-        protected ISampleStore Samples { get; }
+        protected ISampleStore? Samples { get; }
 
         public readonly Live<SkinInfo> SkinInfo;
 
@@ -44,13 +44,15 @@ namespace osu.Game.Skinning
 
         private readonly Dictionary<SkinnableTarget, SkinnableInfo[]> drawableComponentInfo = new Dictionary<SkinnableTarget, SkinnableInfo[]>();
 
-        public abstract ISample GetSample(ISampleInfo sampleInfo);
+        public abstract ISample? GetSample(ISampleInfo sampleInfo);
 
-        public Texture GetTexture(string componentName) => GetTexture(componentName, default, default);
+        public Texture? GetTexture(string componentName) => GetTexture(componentName, default, default);
 
-        public abstract Texture GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
+        public abstract Texture? GetTexture(string componentName, WrapMode wrapModeS, WrapMode wrapModeT);
 
-        public abstract IBindable<TValue> GetConfig<TLookup, TValue>(TLookup lookup);
+        public abstract IBindable<TValue>? GetConfig<TLookup, TValue>(TLookup lookup)
+            where TLookup : notnull
+            where TValue : notnull;
 
         /// <summary>
         /// Construct a new skin.
@@ -59,13 +61,11 @@ namespace osu.Game.Skinning
         /// <param name="resources">Access to game-wide resources.</param>
         /// <param name="storage">An optional store which will *replace* all file lookups that are usually sourced from <paramref name="skin"/>.</param>
         /// <param name="configurationFilename">An optional filename to read the skin configuration from. If not provided, the configuration will be retrieved from the storage using "skin.ini".</param>
-        protected Skin(SkinInfo skin, [CanBeNull] IStorageResourceProvider resources, [CanBeNull] IResourceStore<byte[]> storage = null, [CanBeNull] string configurationFilename = @"skin.ini")
+        protected Skin(SkinInfo skin, IStorageResourceProvider? resources, IResourceStore<byte[]>? storage = null, string configurationFilename = @"skin.ini")
         {
             if (resources != null)
             {
-                SkinInfo = resources.RealmAccess != null
-                    ? skin.ToLive(resources.RealmAccess)
-                    : skin.ToLiveUnmanaged();
+                SkinInfo = skin.ToLive(resources.RealmAccess);
 
                 storage ??= new RealmBackedResourceStore(skin, resources.Files, new[] { @"ogg" });
 
@@ -76,12 +76,20 @@ namespace osu.Game.Skinning
                 Samples = samples;
                 Textures = new TextureStore(resources.CreateTextureLoaderStore(storage));
             }
+            else
+            {
+                // Generally only used for tests.
+                SkinInfo = skin.ToLiveUnmanaged();
+            }
 
             var configurationStream = storage?.GetStream(configurationFilename);
 
             if (configurationStream != null)
+            {
                 // stream will be closed after use by LineBufferedReader.
                 ParseConfigurationStream(configurationStream);
+                Debug.Assert(Configuration != null);
+            }
             else
                 Configuration = new SkinConfiguration();
 
@@ -90,7 +98,7 @@ namespace osu.Game.Skinning
             {
                 string filename = $"{skinnableTarget}.json";
 
-                byte[] bytes = storage?.Get(filename);
+                byte[]? bytes = storage?.Get(filename);
 
                 if (bytes == null)
                     continue;
@@ -136,7 +144,7 @@ namespace osu.Game.Skinning
             DrawableComponentInfo[targetContainer.Target] = targetContainer.CreateSkinnableInfo().ToArray();
         }
 
-        public virtual Drawable GetDrawableComponent(ISkinComponent component)
+        public virtual Drawable? GetDrawableComponent(ISkinComponent component)
         {
             switch (component)
             {
diff --git a/osu.Game/Tests/Visual/SkinnableTestScene.cs b/osu.Game/Tests/Visual/SkinnableTestScene.cs
index b4da91a97a..2e1ca09fe4 100644
--- a/osu.Game/Tests/Visual/SkinnableTestScene.cs
+++ b/osu.Game/Tests/Visual/SkinnableTestScene.cs
@@ -96,7 +96,7 @@ namespace osu.Game.Tests.Visual
                     },
                     new OsuSpriteText
                     {
-                        Text = skin?.SkinInfo?.Value.Name ?? "none",
+                        Text = skin?.SkinInfo.Value.Name ?? "none",
                         Scale = new Vector2(1.5f),
                         Padding = new MarginPadding(5),
                     },