diff --git a/Tests/SaplingEditorTests/EditorLargeDocumentValidationTests.swift b/Tests/SaplingEditorTests/EditorLargeDocumentValidationTests.swift
index c483467..573c2ec 100644
--- a/Tests/SaplingEditorTests/EditorLargeDocumentValidationTests.swift
+++ b/Tests/SaplingEditorTests/EditorLargeDocumentValidationTests.swift
@@ -38,12 +38,11 @@ final class EditorLargeDocumentValidationTests: XCTestCase {
                 previousActiveLineIndex: activeLineIndex,
                 currentActiveLineIndex: activeLineIndex
             )
+            let updatedLineIndex = DocumentLineIndex(source: updatedSource)
             let dirtyRenderMeasurement = elapsedTime {
-                let lines = EditorActiveLineTracker.lines(from: updatedSource, activeLineIndex: activeLineIndex)
-                let dirty = Set(plan.dirtyLineIndexes)
                 let renderer = HybridMarkdownLineRenderer()
-                _ = lines
-                    .filter { dirty.contains($0.index) }
+                _ = plan.dirtyLineIndexes
+                    .compactMap { updatedLineIndex.editorLine(at: $0, activeLineIndex: activeLineIndex) }
                     .map(renderer.renderPlan(for:))
             }