diff --git a/lib/run-status.js b/lib/run-status.js
index 8164bc08e..70791c67f 100644
--- a/lib/run-status.js
+++ b/lib/run-status.js
@@ -18,10 +18,9 @@ function sum(arr, key) {
 }
 
 function normalizeError(err) {
-	if (!isObj(err)) {
+	if (!isObj(err) || typeof err.message !== 'string') {
 		err = {
-			message: err,
-			stack: err
+			message: String(err)
 		};
 	}
 
diff --git a/lib/serialize-error.js b/lib/serialize-error.js
index 6a8c4947b..cbb0a2ac4 100644
--- a/lib/serialize-error.js
+++ b/lib/serialize-error.js
@@ -20,6 +20,11 @@ function filter(propertyName, isRoot, source, target) {
 		return true;
 	}
 
+	if ((propertyName === 'name' || propertyName === 'stack') &&
+		typeof source[propertyName] !== 'string') {
+		return false;
+	}
+
 	if (propertyName === 'stack') {
 		target.stack = beautifyStack(source.stack);
 		return false;
diff --git a/test/run-status.js b/test/run-status.js
index 7783abe5f..9c6a5e5ac 100644
--- a/test/run-status.js
+++ b/test/run-status.js
@@ -87,3 +87,32 @@ test('calculate remaining test count', t => {
 	t.end();
 });
 
+test('handle non-object rejections', t => {
+	const runStatus = new RunStatus();
+
+	runStatus.on('error', err => {
+		t.deepEqual(err, {
+			file: 'foo.js',
+			message: '42',
+			type: 'rejection'
+		});
+		t.end();
+	});
+
+	runStatus.handleRejections({file: 'foo.js', rejections: [42]});
+});
+
+test('handle non-object exceptions', t => {
+	const runStatus = new RunStatus();
+
+	runStatus.on('error', err => {
+		t.deepEqual(err, {
+			file: 'bar.js',
+			message: '/ab/g',
+			type: 'exception'
+		});
+		t.end();
+	});
+
+	runStatus.handleExceptions({file: 'bar.js', exception: /ab/g});
+});
diff --git a/test/serialize-error.js b/test/serialize-error.js
index 27320d85f..305ebd36d 100644
--- a/test/serialize-error.js
+++ b/test/serialize-error.js
@@ -210,3 +210,14 @@ test('does not call toJSON() when serializing actual and expected', t => {
 	t.notSame(serializedErr.actual, serializedErr.expected);
 	t.end();
 });
+
+test('remove non-string error properties', t => {
+	const err = {
+		name: [42],
+		stack: /re/g
+	};
+	const serializedErr = serialize(err);
+	t.is(serializedErr.name, undefined);
+	t.is(serializedErr.stack, undefined);
+	t.end();
+});