diff --git a/index.js b/index.js
index 4c2cbb1f0..e2941e1e2 100644
--- a/index.js
+++ b/index.js
@@ -109,9 +109,14 @@ function handleInput(spawned, input) {
 	}
 }
 
-function handleOutput(options, value) {
-	if (value && options.stripFinalNewline) {
-		value = stripFinalNewline(value);
+function handleOutput(options, value, error) {
+	if (typeof value !== 'string' && !Buffer.isBuffer(value)) {
+		// When `execa.sync()` errors, we normalize it to '' to mimic `execa()`
+		return error === undefined ? undefined : '';
+	}
+
+	if (options.stripFinalNewline) {
+		return stripFinalNewline(value);
 	}
 
 	return value;
@@ -423,8 +428,8 @@ module.exports.sync = (command, args, options) => {
 	}
 
 	const result = childProcess.spawnSync(parsed.command, parsed.args, parsed.options);
-	result.stdout = handleOutput(parsed.options, result.stdout);
-	result.stderr = handleOutput(parsed.options, result.stderr);
+	result.stdout = handleOutput(parsed.options, result.stdout, result.error);
+	result.stderr = handleOutput(parsed.options, result.stderr, result.error);
 
 	if (result.error || result.status !== 0 || result.signal !== null) {
 		const error = makeError(result, {
diff --git a/readme.md b/readme.md
index 7e573f179..ac1d5eb9a 100644
--- a/readme.md
+++ b/readme.md
@@ -107,8 +107,8 @@ try {
 		command: 'wrong command',
 		exitCode: 2,
 		exitCodeName: 'ENOENT',
-		stdout: null,
-		stderr: null,
+		stdout: '',
+		stderr: '',
 		failed: true,
 		timedOut: false,
 		isCanceled: false,
diff --git a/test.js b/test.js
index da64172d9..6544c2671 100644
--- a/test.js
+++ b/test.js
@@ -51,6 +51,40 @@ test('stdout/stderr/all available on errors', async t => {
 	t.is(typeof error.all, 'string');
 });
 
+test('stdout/stderr/all are undefined if ignored', async t => {
+	const {stdout, stderr, all} = await execa('noop', {stdio: 'ignore'});
+	t.is(stdout, undefined);
+	t.is(stderr, undefined);
+	t.is(all, undefined);
+});
+
+test('stdout/stderr/all are undefined if ignored in sync mode', t => {
+	const {stdout, stderr, all} = execa.sync('noop', {stdio: 'ignore'});
+	t.is(stdout, undefined);
+	t.is(stderr, undefined);
+	t.is(all, undefined);
+});
+
+const WRONG_COMMAND_STDERR = process.platform === 'win32' ?
+	'\'wrong\' is not recognized as an internal or external command,\r\noperable program or batch file.' :
+	'';
+
+test('stdout/stderr/all on process errors', async t => {
+	const {stdout, stderr, all} = await t.throwsAsync(execa('wrong command'));
+	t.is(stdout, '');
+	t.is(stderr, WRONG_COMMAND_STDERR);
+	t.is(all, WRONG_COMMAND_STDERR);
+});
+
+test('stdout/stderr/all on process errors, in sync mode', t => {
+	const {stdout, stderr, all} = t.throws(() => {
+		execa.sync('wrong command');
+	});
+	t.is(stdout, '');
+	t.is(stderr, WRONG_COMMAND_STDERR);
+	t.is(all, undefined);
+});
+
 test('pass `stdout` to a file descriptor', async t => {
 	const file = tempfile('.txt');
 	await execa('fixtures/noop', ['foo bar'], {stdout: fs.openSync(file, 'w')});