diff --git a/src/spec-common/commonUtils.ts b/src/spec-common/commonUtils.ts
index b8c5d3786..9b42484ed 100644
--- a/src/spec-common/commonUtils.ts
+++ b/src/spec-common/commonUtils.ts
@@ -42,7 +42,7 @@ export interface ExecFunction {
 
 export interface PtyExec {
 	onData: Event<string>;
-	write(data: string): void;
+	write?(data: string): void;
 	resize(cols: number, rows: number): void;
 	exit: Promise<{ code: number | undefined; signal: number | undefined }>;
 	terminate(): Promise<void>;
@@ -198,14 +198,16 @@ export async function runCommand(options: {
 	return new Promise<{ cmdOutput: string }>((resolve, reject) => {
 		let cmdOutput = '';
 
-		if (stdin) {
-			p.write(stdin);
+		const subs: Disposable[] = [];
+		if (p.write) {
+			if (stdin) {
+				p.write(stdin);
+			}
+			if (onDidInput) {
+				subs.push(onDidInput(data => p.write!(data)));
+			}
 		}
 
-		const subs = [
-			onDidInput && onDidInput(data => p.write(data)),
-		];
-
 		p.onData(chunk => {
 			cmdOutput += chunk;
 			if (print === 'continuous') {
@@ -403,7 +405,7 @@ export function plainExecAsPtyExec(plain: ExecFunction, allowInheritTTY: boolean
 		}
 		return {
 			onData: onDataEmitter.event,
-			write: p.stdin ? p.stdin.write.bind(p.stdin) : () => {},
+			write: p.stdin ? p.stdin.write.bind(p.stdin) : undefined,
 			resize: () => {},
 			exit: p.exit.then(({ code, signal }) => ({
 				code: typeof code === 'number' ? code : undefined,
diff --git a/src/spec-common/injectHeadless.ts b/src/spec-common/injectHeadless.ts
index e7eb550a8..ac51e3950 100644
--- a/src/spec-common/injectHeadless.ts
+++ b/src/spec-common/injectHeadless.ts
@@ -578,10 +578,10 @@ export async function runRemoteCommand(params: { output: Log; onDidInput?: Event
 				}
 			}
 		});
-		if (params.onDidInput) {
-			params.onDidInput(data => p.write(data));
-		} else if (params.stdin) {
-			const listener = (data: Buffer): void => p.write(data.toString());
+		if (p.write && params.onDidInput) {
+			params.onDidInput(data => p.write!(data));
+		} else if (p.write && params.stdin) {
+			const listener = (data: Buffer): void => p.write!(data.toString());
 			const stdin = params.stdin;
 			if (stdin.isTTY) {
 				stdin.setRawMode(true);
diff --git a/src/spec-shutdown/dockerUtils.ts b/src/spec-shutdown/dockerUtils.ts
index e5155bb62..5cd07d0e1 100644
--- a/src/spec-shutdown/dockerUtils.ts
+++ b/src/spec-shutdown/dockerUtils.ts
@@ -311,10 +311,10 @@ export async function dockerComposePtyCLI(params: DockerCLIParameters | PartialP
 	});
 }
 
-export function dockerExecFunction(params: DockerCLIParameters | PartialExecParameters | DockerResolverParameters, containerName: string, user: string | undefined): ExecFunction {
+export function dockerExecFunction(params: DockerCLIParameters | PartialExecParameters | DockerResolverParameters, containerName: string, user: string | undefined, pty = false): ExecFunction {
 	return async function (execParams: ExecParameters): Promise<Exec> {
 		const { exec, cmd, args, env } = toExecParameters(params);
-		const { argsPrefix, args: execArgs } = toDockerExecArgs(containerName, user, execParams, false);
+		const { argsPrefix, args: execArgs } = toDockerExecArgs(containerName, user, execParams, pty);
 		return exec({
 			cmd,
 			args: (args || []).concat(execArgs),
@@ -328,7 +328,7 @@ export function dockerExecFunction(params: DockerCLIParameters | PartialExecPara
 export async function dockerPtyExecFunction(params: PartialPtyExecParameters | DockerResolverParameters, containerName: string, user: string | undefined, loadNativeModule: <T>(moduleName: string) => Promise<T | undefined>, allowInheritTTY: boolean): Promise<PtyExecFunction> {
 	const pty = await loadNativeModule<typeof ptyType>('node-pty');
 	if (!pty) {
-		const plain = dockerExecFunction(params, containerName, user);
+		const plain = dockerExecFunction(params, containerName, user, true);
 		return plainExecAsPtyExec(plain, allowInheritTTY);
 	}