diff --git a/extensions/markdown/src/previewContentProvider.ts b/extensions/markdown/src/previewContentProvider.ts
index e1ce84caba3..ef210649e20 100644
--- a/extensions/markdown/src/previewContentProvider.ts
+++ b/extensions/markdown/src/previewContentProvider.ts
@@ -206,7 +206,7 @@ export class MDDocumentContentProvider implements vscode.TextDocumentContentProv
 		return vscode.workspace.openTextDocument(sourceUri).then(document => {
 			this.config = MarkdownPreviewConfig.getCurrentConfig();
 
-			let initialLine = 0;
+			let initialLine: number | undefined = undefined;
 			const editor = vscode.window.activeTextEditor;
 			if (editor && editor.document.uri.fsPath === sourceUri.fsPath) {
 				initialLine = editor.selection.active.line;