diff --git a/osu.Framework.Tests/Visual/UserInterface/TestSceneScreenStack.cs b/osu.Framework.Tests/Visual/UserInterface/TestSceneScreenStack.cs
index 7fc25442f6..7474f18455 100644
--- a/osu.Framework.Tests/Visual/UserInterface/TestSceneScreenStack.cs
+++ b/osu.Framework.Tests/Visual/UserInterface/TestSceneScreenStack.cs
@@ -1099,7 +1099,7 @@ public override void OnEntering(ScreenTransitionEvent e)
 
                 if (shouldTakeOutLease)
                 {
-                    DummyBindable.BindTo(((TestScreen)e.Last).DummyBindable);
+                    DummyBindable.BindTo(((TestScreen)e.Last!).DummyBindable);
                     LeasedCopy = DummyBindable.BeginLease(true);
                 }
 
diff --git a/osu.Framework/Graphics/UserInterface/Menu.cs b/osu.Framework/Graphics/UserInterface/Menu.cs
index a4e29179aa..cc7823d39e 100644
--- a/osu.Framework/Graphics/UserInterface/Menu.cs
+++ b/osu.Framework/Graphics/UserInterface/Menu.cs
@@ -496,7 +496,7 @@ private void menuItemClicked(DrawableMenuItem item)
             }
 
             // Check if there is a sub menu to display
-            if (item.Item.Items?.Count == 0)
+            if (item.Item.Items.Count == 0)
             {
                 // This item must have attempted to invoke an action - close all menus if item allows
                 if (item.CloseMenuOnClick)
@@ -625,7 +625,7 @@ private void closeFromChild(MenuItem source)
         {
             if (IsHovered || (parentMenu?.IsHovered ?? false)) return;
 
-            if (triggeringItem?.Item.Items?.Contains(source) ?? triggeringItem == null)
+            if (triggeringItem?.Item.Items.Contains(source) ?? triggeringItem == null)
             {
                 Close();
                 parentMenu?.closeFromChild(triggeringItem?.Item);
@@ -834,7 +834,7 @@ public MenuItemState State
             /// </summary>
             protected bool IsActionable => hasSubmenu || (!Item.Action.Disabled && Item.Action.Value != null);
 
-            private bool hasSubmenu => Item.Items?.Count > 0;
+            private bool hasSubmenu => Item.Items.Count > 0;
 
             /// <summary>
             /// Called after the <see cref="BackgroundColour"/> is modified or the hover state changes.
@@ -892,7 +892,7 @@ protected override bool OnClick(ClickEvent e)
                 if (!IsActionable)
                     return true;
 
-                Item.Action.Value.Invoke();
+                Item.Action.Value?.Invoke();
                 Clicked?.Invoke(this);
                 return true;
             }
diff --git a/osu.Framework/IO/Stores/FontStore.cs b/osu.Framework/IO/Stores/FontStore.cs
index 6893c247df..0ad9094bc3 100644
--- a/osu.Framework/IO/Stores/FontStore.cs
+++ b/osu.Framework/IO/Stores/FontStore.cs
@@ -6,6 +6,7 @@
 using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Threading.Tasks;
+using osu.Framework.Extensions.ObjectExtensions;
 using osu.Framework.Graphics.Rendering;
 using osu.Framework.Graphics.Textures;
 using osu.Framework.Logging;
@@ -142,7 +143,7 @@ public ITexturedCharacterGlyph Get(string fontName, char character)
             foreach (var store in glyphStores)
             {
                 if ((string.IsNullOrEmpty(fontName) || fontName == store.FontName) && store.HasGlyph(character))
-                    return namespacedGlyphCache[key] = new TexturedCharacterGlyph(store.Get(character), Get(textureName), 1 / ScaleAdjust);
+                    return namespacedGlyphCache[key] = new TexturedCharacterGlyph(store.Get(character).AsNonNull(), Get(textureName), 1 / ScaleAdjust);
             }
 
             foreach (var store in nestedFontStores)
diff --git a/osu.Framework/Input/Events/FocusEvent.cs b/osu.Framework/Input/Events/FocusEvent.cs
index 2bee21d3e0..2c7fba00f0 100644
--- a/osu.Framework/Input/Events/FocusEvent.cs
+++ b/osu.Framework/Input/Events/FocusEvent.cs
@@ -16,7 +16,7 @@ public class FocusEvent : UIEvent
         /// </summary>
         public readonly Drawable? PreviouslyFocused;
 
-        public FocusEvent(InputState state, Drawable previouslyFocused)
+        public FocusEvent(InputState state, Drawable? previouslyFocused)
             : base(state)
         {
             PreviouslyFocused = previouslyFocused;
diff --git a/osu.Framework/Input/PassThroughInputManager.cs b/osu.Framework/Input/PassThroughInputManager.cs
index f905ce5b46..014fa8afd9 100644
--- a/osu.Framework/Input/PassThroughInputManager.cs
+++ b/osu.Framework/Input/PassThroughInputManager.cs
@@ -3,6 +3,7 @@
 
 #nullable disable
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using osu.Framework.Graphics;
@@ -181,13 +182,13 @@ protected virtual void SyncInputState(InputState state)
             new TouchInput(touchStateDifference.deactivated, false).Apply(CurrentState, this);
             new TouchInput(touchStateDifference.activated, true).Apply(CurrentState, this);
 
-            new JoystickButtonInput(state?.Joystick?.Buttons, CurrentState.Joystick.Buttons).Apply(CurrentState, this);
-            new JoystickAxisInput(state?.Joystick?.GetAxes()).Apply(CurrentState, this);
+            new JoystickButtonInput(state?.Joystick?.Buttons ?? new ButtonStates<JoystickButton>(), CurrentState.Joystick.Buttons).Apply(CurrentState, this);
+            new JoystickAxisInput(state?.Joystick?.GetAxes() ?? Array.Empty<JoystickAxis>()).Apply(CurrentState, this);
 
-            new MidiKeyInput(state?.Midi, CurrentState.Midi).Apply(CurrentState, this);
+            new MidiKeyInput(state?.Midi ?? new MidiState(), CurrentState.Midi).Apply(CurrentState, this);
 
-            new TabletPenButtonInput(state?.Tablet.PenButtons, CurrentState.Tablet.PenButtons).Apply(CurrentState, this);
-            new TabletAuxiliaryButtonInput(state?.Tablet.AuxiliaryButtons, CurrentState.Tablet.AuxiliaryButtons).Apply(CurrentState, this);
+            new TabletPenButtonInput(state?.Tablet.PenButtons ?? new ButtonStates<TabletPenButton>(), CurrentState.Tablet.PenButtons).Apply(CurrentState, this);
+            new TabletAuxiliaryButtonInput(state?.Tablet.AuxiliaryButtons ?? new ButtonStates<TabletAuxiliaryButton>(), CurrentState.Tablet.AuxiliaryButtons).Apply(CurrentState, this);
         }
     }
 }
diff --git a/osu.Framework/Screens/ScreenTransitionEvent.cs b/osu.Framework/Screens/ScreenTransitionEvent.cs
index 052dc5a442..e2d4309a19 100644
--- a/osu.Framework/Screens/ScreenTransitionEvent.cs
+++ b/osu.Framework/Screens/ScreenTransitionEvent.cs
@@ -11,14 +11,14 @@ public class ScreenTransitionEvent
         /// <summary>
         /// The <see cref="IScreen"/> which has been transitioned from.
         /// </summary>
-        public IScreen Last { get; }
+        public IScreen? Last { get; }
 
         /// <summary>
         /// The <see cref="IScreen"/> which has been transitioned to.
         /// </summary>
         public IScreen Next { get; }
 
-        public ScreenTransitionEvent(IScreen last, IScreen next)
+        public ScreenTransitionEvent(IScreen? last, IScreen next)
         {
             Last = last;
             Next = next;
diff --git a/osu.Framework/Testing/Drawables/Steps/ToggleStepButton.cs b/osu.Framework/Testing/Drawables/Steps/ToggleStepButton.cs
index a702e357e4..5d2b7d8857 100644
--- a/osu.Framework/Testing/Drawables/Steps/ToggleStepButton.cs
+++ b/osu.Framework/Testing/Drawables/Steps/ToggleStepButton.cs
@@ -9,7 +9,7 @@ namespace osu.Framework.Testing.Drawables.Steps
 {
     public partial class ToggleStepButton : StepButton
     {
-        private readonly Action<bool> reloadCallback;
+        private readonly Action<bool>? reloadCallback;
         private static readonly Color4 off_colour = Color4.Red;
         private static readonly Color4 on_colour = Color4.YellowGreen;
 
@@ -17,7 +17,7 @@ public partial class ToggleStepButton : StepButton
 
         public override int RequiredRepetitions => 2;
 
-        public ToggleStepButton(Action<bool> reloadCallback)
+        public ToggleStepButton(Action<bool>? reloadCallback)
         {
             this.reloadCallback = reloadCallback;
             Action = clickAction;
@@ -28,7 +28,7 @@ private void clickAction()
         {
             State = !State;
             Light.FadeColour(State ? on_colour : off_colour);
-            reloadCallback.Invoke(State);
+            reloadCallback?.Invoke(State);
 
             if (!State)
                 Success();
diff --git a/osu.Framework/Text/TextBuilder.cs b/osu.Framework/Text/TextBuilder.cs
index 7adb636f48..012410812f 100644
--- a/osu.Framework/Text/TextBuilder.cs
+++ b/osu.Framework/Text/TextBuilder.cs
@@ -356,9 +356,9 @@ private bool tryCreateGlyph(char character, out TextBuilderGlyph glyph)
         private ITexturedCharacterGlyph getTexturedGlyph(char character)
         {
             return store.Get(font.FontName, character)
-                   ?? store.Get(null, character)
+                   ?? store.Get(string.Empty, character)
                    ?? store.Get(font.FontName, fallbackCharacter)
-                   ?? store.Get(null, fallbackCharacter);
+                   ?? store.Get(string.Empty, fallbackCharacter);
         }
     }
 }