diff --git a/osu.Game/Graphics/UserInterface/OsuNumberBox.cs b/osu.Game/Graphics/UserInterface/OsuNumberBox.cs
index 36288c745a..3d565a4464 100644
--- a/osu.Game/Graphics/UserInterface/OsuNumberBox.cs
+++ b/osu.Game/Graphics/UserInterface/OsuNumberBox.cs
@@ -1,10 +1,12 @@
 // 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 osu.Framework.Extensions;
+
 namespace osu.Game.Graphics.UserInterface
 {
     public class OsuNumberBox : OsuTextBox
     {
-        protected override bool CanAddCharacter(char character) => char.IsNumber(character);
+        protected override bool CanAddCharacter(char character) => character.IsAsciiDigit();
     }
 }
diff --git a/osu.Game/Overlays/Settings/SettingsNumberBox.cs b/osu.Game/Overlays/Settings/SettingsNumberBox.cs
index 0a4949f8b6..cc4446033a 100644
--- a/osu.Game/Overlays/Settings/SettingsNumberBox.cs
+++ b/osu.Game/Overlays/Settings/SettingsNumberBox.cs
@@ -2,6 +2,7 @@
 // See the LICENCE file in the repository root for full licence text.
 
 using osu.Framework.Bindables;
+using osu.Framework.Extensions;
 using osu.Framework.Graphics;
 using osu.Framework.Graphics.Containers;
 using osu.Framework.Graphics.UserInterface;
@@ -67,7 +68,7 @@ namespace osu.Game.Overlays.Settings
 
         private class OutlinedNumberBox : OutlinedTextBox
         {
-            protected override bool CanAddCharacter(char character) => character >= '0' && character <= '9';
+            protected override bool CanAddCharacter(char character) => character.IsAsciiDigit();
 
             public new void NotifyInputError() => base.NotifyInputError();
         }