diff --git a/extensions/typescript-language-features/src/typescriptServiceClient.ts b/extensions/typescript-language-features/src/typescriptServiceClient.ts
index a56c6d77f75..430813d3ad6 100644
--- a/extensions/typescript-language-features/src/typescriptServiceClient.ts
+++ b/extensions/typescript-language-features/src/typescriptServiceClient.ts
@@ -710,16 +710,20 @@ export default class TypeScriptServiceClient extends Disposable implements IType
 			return undefined;
 		}
 
-		if (resource.scheme === fileSchemes.file || resource.scheme === fileSchemes.untitled) {
-			for (const root of roots.sort((a, b) => a.uri.fsPath.length - b.uri.fsPath.length)) {
-				if (resource.fsPath.startsWith(root.uri.fsPath + path.sep)) {
-					return root.uri.fsPath;
+		switch (resource.scheme) {
+			case fileSchemes.file:
+			case fileSchemes.untitled:
+			case fileSchemes.vscodeNotebookCell:
+				for (const root of roots.sort((a, b) => a.uri.fsPath.length - b.uri.fsPath.length)) {
+					if (resource.fsPath.startsWith(root.uri.fsPath + path.sep)) {
+						return root.uri.fsPath;
+					}
 				}
-			}
-			return roots[0].uri.fsPath;
-		}
+				return roots[0].uri.fsPath;
 
-		return undefined;
+			default:
+				return undefined;
+		}
 	}
 
 	public execute(command: keyof TypeScriptRequests, args: any, token: vscode.CancellationToken, config?: ExecConfig): Promise<ServerResponse.Response<Proto.Response>> {