diff --git a/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs b/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
index 0a2cd75f8..240ac9395 100644
--- a/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
+++ b/ICSharpCode.Decompiler/CSharp/CSharpDecompiler.cs
@@ -32,7 +32,6 @@ using ICSharpCode.Decompiler.CSharp.OutputVisitor;
 using ICSharpCode.Decompiler.CSharp.Resolver;
 using ICSharpCode.Decompiler.CSharp.Syntax;
 using ICSharpCode.Decompiler.CSharp.Transforms;
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.DebugSteps;
 using ICSharpCode.Decompiler.DebugInfo;
 using ICSharpCode.Decompiler.Disassembler;
@@ -44,6 +43,7 @@ using ICSharpCode.Decompiler.Instrumentation;
 using ICSharpCode.Decompiler.Metadata;
 using ICSharpCode.Decompiler.Semantics;
 using ICSharpCode.Decompiler.TypeSystem;
+using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.Decompiler.Util;
 
 using SRM = System.Reflection.Metadata;
diff --git a/ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs b/ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs
index 231c00890..20b0ca445 100644
--- a/ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs
+++ b/ICSharpCode.Decompiler/CSharp/ExpressionBuilder.cs
@@ -28,7 +28,6 @@ using System.Threading;
 using ICSharpCode.Decompiler.CSharp.Resolver;
 using ICSharpCode.Decompiler.CSharp.Syntax;
 using ICSharpCode.Decompiler.CSharp.Transforms;
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.IL;
 using ICSharpCode.Decompiler.IL.Transforms;
 using ICSharpCode.Decompiler.Semantics;
diff --git a/ICSharpCode.Decompiler/CSharp/Resolver/CSharpResolver.cs b/ICSharpCode.Decompiler/CSharp/Resolver/CSharpResolver.cs
index 06ff69a16..862983865 100644
--- a/ICSharpCode.Decompiler/CSharp/Resolver/CSharpResolver.cs
+++ b/ICSharpCode.Decompiler/CSharp/Resolver/CSharpResolver.cs
@@ -23,7 +23,6 @@ using System.Diagnostics;
 using System.Linq;
 
 using ICSharpCode.Decompiler.CSharp.Syntax;
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.Semantics;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
diff --git a/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs b/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs
index 696277501..70c880fd0 100644
--- a/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs
+++ b/ICSharpCode.Decompiler/CSharp/Syntax/TypeSystemAstBuilder.cs
@@ -27,7 +27,6 @@ using System.Reflection.Metadata.Ecma335;
 using System.Runtime.CompilerServices;
 
 using ICSharpCode.Decompiler.CSharp.Resolver;
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.Semantics;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
diff --git a/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceExtensionMethods.cs b/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceExtensionMethods.cs
index 7cb5ac668..edde48815 100644
--- a/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceExtensionMethods.cs
+++ b/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceExtensionMethods.cs
@@ -25,9 +25,9 @@ using System.Linq;
 
 using ICSharpCode.Decompiler.CSharp.Resolver;
 using ICSharpCode.Decompiler.CSharp.Syntax;
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.Semantics;
 using ICSharpCode.Decompiler.TypeSystem;
+using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.Decompiler.Util;
 
 namespace ICSharpCode.Decompiler.CSharp.Transforms
diff --git a/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceUsingDeclarations.cs b/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceUsingDeclarations.cs
index 7144e718f..b953e0652 100644
--- a/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceUsingDeclarations.cs
+++ b/ICSharpCode.Decompiler/CSharp/Transforms/IntroduceUsingDeclarations.cs
@@ -29,7 +29,6 @@ using ICSharpCode.Decompiler.CSharp.Syntax;
 #if STEP
 using ICSharpCode.Decompiler.CSharp.Syntax.PatternMatching;
 #endif
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.IL;
 using ICSharpCode.Decompiler.Semantics;
 using ICSharpCode.Decompiler.TypeSystem;
diff --git a/ICSharpCode.Decompiler/DecompileRun.cs b/ICSharpCode.Decompiler/DecompileRun.cs
index 10cb42fda..8f9242aef 100644
--- a/ICSharpCode.Decompiler/DecompileRun.cs
+++ b/ICSharpCode.Decompiler/DecompileRun.cs
@@ -46,9 +46,9 @@ namespace ICSharpCode.Decompiler
 
 		public Dictionary<ITypeDefinition, bool> TypeHierarchyIsKnown { get; } = new();
 
-		public CSharp.TypeSystem.UsingScope UsingScope { get; }
+		public UsingScope UsingScope { get; }
 
-		public DecompileRun(DecompilerSettings settings, CSharp.TypeSystem.UsingScope usingScope)
+		public DecompileRun(DecompilerSettings settings, UsingScope usingScope)
 		{
 			this.Settings = settings ?? throw new ArgumentNullException(nameof(settings));
 			this.UsingScope = usingScope ?? throw new ArgumentNullException(nameof(usingScope));
diff --git a/ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs b/ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs
index 2aa1f5a4d..3e626d956 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/AssignVariableNames.cs
@@ -29,7 +29,6 @@ using Humanizer.Inflections;
 using ICSharpCode.Decompiler.CSharp;
 using ICSharpCode.Decompiler.CSharp.OutputVisitor;
 using ICSharpCode.Decompiler.CSharp.Transforms;
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem;
 using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.Decompiler.Util;
diff --git a/ICSharpCode.Decompiler/IL/Transforms/IILTransform.cs b/ICSharpCode.Decompiler/IL/Transforms/IILTransform.cs
index 4c00a8871..e56b1cc3e 100644
--- a/ICSharpCode.Decompiler/IL/Transforms/IILTransform.cs
+++ b/ICSharpCode.Decompiler/IL/Transforms/IILTransform.cs
@@ -24,10 +24,10 @@ using System.Diagnostics;
 using System.Threading;
 
 using ICSharpCode.Decompiler.CSharp.Resolver;
-using ICSharpCode.Decompiler.CSharp.TypeSystem;
 using ICSharpCode.Decompiler.DebugSteps;
 using ICSharpCode.Decompiler.DebugInfo;
 using ICSharpCode.Decompiler.TypeSystem;
+using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.Decompiler.Util;
 
 namespace ICSharpCode.Decompiler.IL.Transforms
diff --git a/ICSharpCode.Decompiler/CSharp/TypeSystem/CSharpTypeResolveContext.cs b/ICSharpCode.Decompiler/TypeSystem/Implementation/CSharpTypeResolveContext.cs
similarity index 97%
rename from ICSharpCode.Decompiler/CSharp/TypeSystem/CSharpTypeResolveContext.cs
rename to ICSharpCode.Decompiler/TypeSystem/Implementation/CSharpTypeResolveContext.cs
index 7cf1716b6..f2999d198 100644
--- a/ICSharpCode.Decompiler/CSharp/TypeSystem/CSharpTypeResolveContext.cs
+++ b/ICSharpCode.Decompiler/TypeSystem/Implementation/CSharpTypeResolveContext.cs
@@ -18,9 +18,7 @@
 
 using System;
 
-using ICSharpCode.Decompiler.TypeSystem;
-
-namespace ICSharpCode.Decompiler.CSharp.TypeSystem
+namespace ICSharpCode.Decompiler.TypeSystem.Implementation
 {
 	public sealed class CSharpTypeResolveContext : ITypeResolveContext
 	{
diff --git a/ICSharpCode.Decompiler/CSharp/TypeSystem/UsingScope.cs b/ICSharpCode.Decompiler/TypeSystem/UsingScope.cs
similarity index 97%
rename from ICSharpCode.Decompiler/CSharp/TypeSystem/UsingScope.cs
rename to ICSharpCode.Decompiler/TypeSystem/UsingScope.cs
index 545f83694..374d5ee4d 100644
--- a/ICSharpCode.Decompiler/CSharp/TypeSystem/UsingScope.cs
+++ b/ICSharpCode.Decompiler/TypeSystem/UsingScope.cs
@@ -23,12 +23,12 @@ using System.Collections.Immutable;
 
 using ICSharpCode.Decompiler.CSharp.Syntax;
 using ICSharpCode.Decompiler.Semantics;
-using ICSharpCode.Decompiler.TypeSystem;
+using ICSharpCode.Decompiler.TypeSystem.Implementation;
 using ICSharpCode.Decompiler.Util;
 
 #nullable enable
 
-namespace ICSharpCode.Decompiler.CSharp.TypeSystem
+namespace ICSharpCode.Decompiler.TypeSystem
 {
 	/// <summary>
 	/// Represents a scope that contains "using" statements.