diff --git a/src/EditorFeatures/Core/Preview/AbstractPreviewFactoryService.cs b/src/EditorFeatures/Core/Preview/AbstractPreviewFactoryService.cs
index 7021b039a64e1..ddf867141412a 100644
--- a/src/EditorFeatures/Core/Preview/AbstractPreviewFactoryService.cs
+++ b/src/EditorFeatures/Core/Preview/AbstractPreviewFactoryService.cs
@@ -709,6 +709,10 @@ private async ValueTask<IDifferenceViewerPreview<TDifferenceViewer>> CreateNewDi
 
             rightWorkspace?.Dispose();
             rightWorkspace = null;
+
+            var inertContentType = _contentTypeRegistryService.GetContentType(StandardContentTypeNames.Inert);
+            originalBuffer.ChangeContentType(inertContentType, null);
+            changedBuffer.ChangeContentType(inertContentType, null);
         };
 
         return CreateDifferenceViewerPreview(diffViewer);