diff --git a/src/Avalonia.Base/Media/BoxShadows.cs b/src/Avalonia.Base/Media/BoxShadows.cs
index 44288d89cf..ab2694389f 100644
--- a/src/Avalonia.Base/Media/BoxShadows.cs
+++ b/src/Avalonia.Base/Media/BoxShadows.cs
@@ -1,7 +1,7 @@
 using System;
 using System.ComponentModel;
-using System.Text;
 using Avalonia.Animation.Animators;
+using Avalonia.Utilities;
 
 namespace Avalonia.Media
 {
diff --git a/src/Avalonia.Base/Styling/NthChildSelector.cs b/src/Avalonia.Base/Styling/NthChildSelector.cs
index a7ba79696e..c872a40ad4 100644
--- a/src/Avalonia.Base/Styling/NthChildSelector.cs
+++ b/src/Avalonia.Base/Styling/NthChildSelector.cs
@@ -1,8 +1,8 @@
 #nullable enable
 using System;
-using System.Text;
 using Avalonia.LogicalTree;
 using Avalonia.Styling.Activators;
+using Avalonia.Utilities;
 
 namespace Avalonia.Styling
 {
diff --git a/src/Avalonia.Base/Styling/PropertyEqualsSelector.cs b/src/Avalonia.Base/Styling/PropertyEqualsSelector.cs
index 8922b939f7..e98ff3f9c9 100644
--- a/src/Avalonia.Base/Styling/PropertyEqualsSelector.cs
+++ b/src/Avalonia.Base/Styling/PropertyEqualsSelector.cs
@@ -1,8 +1,8 @@
 using System;
 using System.ComponentModel;
 using System.Globalization;
-using System.Text;
 using Avalonia.Styling.Activators;
+using Avalonia.Utilities;
 
 #nullable enable
 
diff --git a/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs b/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs
index 698d96d0aa..1833f0d133 100644
--- a/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs
+++ b/src/Avalonia.Base/Styling/TypeNameAndClassSelector.cs
@@ -1,8 +1,8 @@
 using System;
 using System.Collections.Generic;
-using System.Text;
 using Avalonia.Controls;
 using Avalonia.Styling.Activators;
+using Avalonia.Utilities;
 
 #nullable enable
 
diff --git a/src/Avalonia.Base/StringBuilderCache.cs b/src/Avalonia.Base/Utilities/StringBuilderCache.cs
similarity index 98%
rename from src/Avalonia.Base/StringBuilderCache.cs
rename to src/Avalonia.Base/Utilities/StringBuilderCache.cs
index 060d76090a..be8b24c848 100644
--- a/src/Avalonia.Base/StringBuilderCache.cs
+++ b/src/Avalonia.Base/Utilities/StringBuilderCache.cs
@@ -8,7 +8,7 @@
 using System;
 using System.Text;
 
-namespace Avalonia;
+namespace Avalonia.Utilities;
 
 // <summary>Provide a cached reusable instance of stringbuilder per thread.</summary>
 internal static class StringBuilderCache
diff --git a/src/Avalonia.Build.Tasks/Avalonia.Build.Tasks.csproj b/src/Avalonia.Build.Tasks/Avalonia.Build.Tasks.csproj
index a5e38a86a2..7e1cb76911 100644
--- a/src/Avalonia.Build.Tasks/Avalonia.Build.Tasks.csproj
+++ b/src/Avalonia.Build.Tasks/Avalonia.Build.Tasks.csproj
@@ -50,7 +50,7 @@
       <Compile Include="../Avalonia.Base/Utilities/MathUtilities.cs">
         <Link>Markup/%(RecursiveDir)%(FileName)%(Extension)</Link>
       </Compile>
-      <Compile Include="..\Avalonia.Base\StringBuilderCache.cs" Link="StringBuilderCache.cs" />
+      <Compile Include="..\Avalonia.Base\Utilities\StringBuilderCache.cs" Link="Utilities\StringBuilderCache.cs" />
       <Compile Include="..\Markup\Avalonia.Markup\Markup\Parsers\ArgumentListParser.cs">
         <Link>Markup/%(RecursiveDir)%(FileName)%(Extension)</Link>
       </Compile>
diff --git a/src/Avalonia.Controls.ColorPicker/Helpers/ColorHelper.cs b/src/Avalonia.Controls.ColorPicker/Helpers/ColorHelper.cs
index 68aa30ea7a..c1a03b1b77 100644
--- a/src/Avalonia.Controls.ColorPicker/Helpers/ColorHelper.cs
+++ b/src/Avalonia.Controls.ColorPicker/Helpers/ColorHelper.cs
@@ -2,7 +2,7 @@
 using System.Globalization;
 using System.Collections.Generic;
 using Avalonia.Media;
-using System.Text;
+using Avalonia.Utilities;
 
 namespace Avalonia.Controls.Primitives
 {
diff --git a/src/Avalonia.Controls/Converters/PlatformKeyGestureConverter.cs b/src/Avalonia.Controls/Converters/PlatformKeyGestureConverter.cs
index 47c2f94e18..0fa43809ac 100644
--- a/src/Avalonia.Controls/Converters/PlatformKeyGestureConverter.cs
+++ b/src/Avalonia.Controls/Converters/PlatformKeyGestureConverter.cs
@@ -4,6 +4,7 @@ using System.Runtime.InteropServices;
 using System.Text;
 using Avalonia.Data.Converters;
 using Avalonia.Input;
+using Avalonia.Utilities;
 
 namespace Avalonia.Controls.Converters
 {
diff --git a/src/Avalonia.Controls/Documents/InlineCollection.cs b/src/Avalonia.Controls/Documents/InlineCollection.cs
index 81ccff4cbd..190373169b 100644
--- a/src/Avalonia.Controls/Documents/InlineCollection.cs
+++ b/src/Avalonia.Controls/Documents/InlineCollection.cs
@@ -1,8 +1,8 @@
 using System;
-using System.Text;
 using Avalonia.Collections;
 using Avalonia.LogicalTree;
 using Avalonia.Metadata;
+using Avalonia.Utilities;
 
 namespace Avalonia.Controls.Documents
 {
diff --git a/src/Windows/Avalonia.Win32/ClipboardFormats.cs b/src/Windows/Avalonia.Win32/ClipboardFormats.cs
index f5b8cd6b96..7bd7765f8c 100644
--- a/src/Windows/Avalonia.Win32/ClipboardFormats.cs
+++ b/src/Windows/Avalonia.Win32/ClipboardFormats.cs
@@ -2,9 +2,9 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
-using System.Text;
 using Avalonia.Input;
 using Avalonia.Win32.Interop;
+using Avalonia.Utilities;
 
 namespace Avalonia.Win32
 {
diff --git a/src/Windows/Avalonia.Win32/Input/WindowsKeyboardDevice.cs b/src/Windows/Avalonia.Win32/Input/WindowsKeyboardDevice.cs
index 878011b5aa..7e1e22579b 100644
--- a/src/Windows/Avalonia.Win32/Input/WindowsKeyboardDevice.cs
+++ b/src/Windows/Avalonia.Win32/Input/WindowsKeyboardDevice.cs
@@ -1,6 +1,6 @@
-using System.Text;
 using Avalonia.Controls;
 using Avalonia.Input;
+using Avalonia.Utilities;
 using Avalonia.Win32.Interop;
 
 namespace Avalonia.Win32.Input
diff --git a/src/Windows/Avalonia.Win32/OleDataObject.cs b/src/Windows/Avalonia.Win32/OleDataObject.cs
index 837b21e34f..f7345b3ff7 100644
--- a/src/Windows/Avalonia.Win32/OleDataObject.cs
+++ b/src/Windows/Avalonia.Win32/OleDataObject.cs
@@ -6,9 +6,9 @@ using System.Linq;
 using System.Runtime.InteropServices;
 using System.Runtime.InteropServices.ComTypes;
 using System.Runtime.Serialization.Formatters.Binary;
-using System.Text;
 using Avalonia.Input;
 using Avalonia.MicroCom;
+using Avalonia.Utilities;
 using Avalonia.Win32.Interop;
 
 using IDataObject = Avalonia.Input.IDataObject;
diff --git a/src/tools/Avalonia.Designer.HostApp/Avalonia.Designer.HostApp.csproj b/src/tools/Avalonia.Designer.HostApp/Avalonia.Designer.HostApp.csproj
index 3dfef234a9..3293066dd1 100644
--- a/src/tools/Avalonia.Designer.HostApp/Avalonia.Designer.HostApp.csproj
+++ b/src/tools/Avalonia.Designer.HostApp/Avalonia.Designer.HostApp.csproj
@@ -16,7 +16,7 @@
   <ItemGroup>
     <Compile Include="..\..\..\src\Markup\Avalonia.Markup.Xaml.Loader\CompilerExtensions\**\*.cs" />
     <Compile Include="..\..\..\src\Markup\Avalonia.Markup.Xaml.Loader\AvaloniaXamlIlRuntimeCompiler.cs" />
-    <Compile Include="..\..\Avalonia.Base\StringBuilderCache.cs" Link="StringBuilderCache.cs" />
+    <Compile Include="..\..\Avalonia.Base\Utilities\StringBuilderCache.cs" Link="Utilities\StringBuilderCache.cs" />
   </ItemGroup>
   <ItemGroup>
     <PackageReference Include="Avalonia.Angle.Windows.Natives" Version="2.1.0.2020091801" />