diff --git a/src/DotNetPad/DotNetPad.Applications/DotNetPad.Applications.csproj b/src/DotNetPad/DotNetPad.Applications/DotNetPad.Applications.csproj
index c459248..887dd03 100644
--- a/src/DotNetPad/DotNetPad.Applications/DotNetPad.Applications.csproj
+++ b/src/DotNetPad/DotNetPad.Applications/DotNetPad.Applications.csproj
@@ -6,7 +6,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Waf.Wpf" Version="7.0.1-alpha.0.51" />
+    <PackageReference Include="System.Waf.Wpf" Version="7.0.1-alpha.0.53" />
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Features" Version="4.8.0-3.final" />
     <PackageReference Include="Microsoft.CodeAnalysis.VisualBasic.Features" Version="4.8.0-3.final" />
   </ItemGroup>
diff --git a/src/DotNetPad/DotNetPad.Applications/Services/FileService.cs b/src/DotNetPad/DotNetPad.Applications/Services/FileService.cs
index 7ff7c58..50b1182 100644
--- a/src/DotNetPad/DotNetPad.Applications/Services/FileService.cs
+++ b/src/DotNetPad/DotNetPad.Applications/Services/FileService.cs
@@ -25,10 +25,10 @@ internal sealed class FileService : Model, IFileService
     public FileService()
     {
         documentFiles = [];
-        DocumentFiles = new(documentFiles);
+        DocumentFiles = new ReadOnlyObservableList<DocumentFile>(documentFiles);
     }
 
-    public ReadOnlyObservableList<DocumentFile> DocumentFiles { get; }
+    public IReadOnlyObservableList<DocumentFile> DocumentFiles { get; }
 
     public DocumentFile? ActiveDocumentFile
     {
diff --git a/src/DotNetPad/DotNetPad.Applications/Services/IDocumentService.cs b/src/DotNetPad/DotNetPad.Applications/Services/IDocumentService.cs
index 6701bb1..65b56ce 100644
--- a/src/DotNetPad/DotNetPad.Applications/Services/IDocumentService.cs
+++ b/src/DotNetPad/DotNetPad.Applications/Services/IDocumentService.cs
@@ -4,7 +4,7 @@ namespace Waf.DotNetPad.Applications.Services;
 
 public interface IDocumentService : INotifyPropertyChanged
 {
-    ReadOnlyObservableList<DocumentFile> DocumentFiles { get; }
+    IReadOnlyObservableList<DocumentFile> DocumentFiles { get; }
         
     DocumentFile? ActiveDocumentFile { get; set; }
 
diff --git a/src/DotNetPad/DotNetPad.Domain/DotNetPad.Domain.csproj b/src/DotNetPad/DotNetPad.Domain/DotNetPad.Domain.csproj
index ba807de..3e2ba3d 100644
--- a/src/DotNetPad/DotNetPad.Domain/DotNetPad.Domain.csproj
+++ b/src/DotNetPad/DotNetPad.Domain/DotNetPad.Domain.csproj
@@ -6,6 +6,6 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="System.Waf.Core" Version="7.0.1-alpha.0.51" />
+    <PackageReference Include="System.Waf.Core" Version="7.0.1-alpha.0.53" />
   </ItemGroup>
 </Project>
\ No newline at end of file
diff --git a/src/DotNetPad/DotNetPad.Presentation/DesignData/MockDocumentService.cs b/src/DotNetPad/DotNetPad.Presentation/DesignData/MockDocumentService.cs
index ffea0d7..e780c39 100644
--- a/src/DotNetPad/DotNetPad.Presentation/DesignData/MockDocumentService.cs
+++ b/src/DotNetPad/DotNetPad.Presentation/DesignData/MockDocumentService.cs
@@ -5,7 +5,7 @@ namespace Waf.DotNetPad.Presentation.DesignData;
 
 internal sealed class MockDocumentService : Model, IDocumentService
 {
-    public ReadOnlyObservableList<DocumentFile> DocumentFiles { get; set; } = null!;
+    public IReadOnlyObservableList<DocumentFile> DocumentFiles { get; set; } = null!;
         
     public DocumentFile? ActiveDocumentFile { get; set; }
 
diff --git a/src/DotNetPad/DotNetPad.Presentation/DesignData/MockFileService.cs b/src/DotNetPad/DotNetPad.Presentation/DesignData/MockFileService.cs
index 5e1ee78..4aca630 100644
--- a/src/DotNetPad/DotNetPad.Presentation/DesignData/MockFileService.cs
+++ b/src/DotNetPad/DotNetPad.Presentation/DesignData/MockFileService.cs
@@ -25,7 +25,7 @@ public class MockFileService : Model, IFileService
 
     public ICommand SaveAsCommand { get; set; } = null!;
 
-    public ReadOnlyObservableList<DocumentFile> DocumentFiles { get; set; } = null!;
+    public IReadOnlyObservableList<DocumentFile> DocumentFiles { get; set; } = null!;
         
     public DocumentFile? ActiveDocumentFile { get; set; }