diff --git a/src/Features/Core/Portable/SolutionCrawler/WorkCoordinator.cs b/src/Features/Core/Portable/SolutionCrawler/WorkCoordinator.cs
index 5843bfd9f4de118b2d7b120cc389cc1b1e2cc916..26c5c7d7d3e5563d42c3364c4609390d4c90250f 100644
--- a/src/Features/Core/Portable/SolutionCrawler/WorkCoordinator.cs
+++ b/src/Features/Core/Portable/SolutionCrawler/WorkCoordinator.cs
@@ -543,7 +543,14 @@ private async Task EnqueueProjectConfigurationChangeWorkItemAsync(ProjectChanges
             private async Task EnqueueWorkItemAsync(Document oldDocument, Document newDocument)
             {
                 var differenceService = newDocument.GetLanguageService<IDocumentDifferenceService>();
-                if (differenceService != null)
+
+                if (differenceService == null)
+                {
+                    /// For languages that don't use a Roslyn syntax tree, they don't export a <see cref="IDocumentDifferenceService"/>
+                    /// So we should consider the whole document changed.
+                    await EnqueueWorkItemAsync(newDocument, InvocationReasons.DocumentChanged).ConfigureAwait(false);
+                }
+                else
                 {
                     var differenceResult = await differenceService.GetDifferenceAsync(oldDocument, newDocument, _shutdownToken).ConfigureAwait(false);