diff --git a/__tests__/write/heosCommand.ts b/__tests__/write/heosCommand.ts
index 08d710c..b71d408 100644
--- a/__tests__/write/heosCommand.ts
+++ b/__tests__/write/heosCommand.ts
@@ -17,7 +17,7 @@ describe('Heos commands can be correctly created', () => {
 		expect(command).toEqual('heos://player/volume_up?pid=2&step=5\r\n')
 	})
 
-	test('A command can have no attributes', () => {
+	test('A command can have zero attributes', () => {
 		const command = generateHeosCommand('system', 'heart_beat', {})
 
 		expect(command).toEqual('heos://system/heart_beat\r\n')
@@ -28,4 +28,12 @@ describe('Heos commands can be correctly created', () => {
 
 		expect(command).toEqual('heos://player/get_volume?pid=1\r\n')
 	})
+
+	test('Strings are correctly encoded', () => {
+		const command = generateHeosCommand('system', 'register_for_change_events', {
+			enable: 'on'
+		})
+
+		expect(command).toEqual('heos://system/register_for_change_events?enable=on\r\n')
+	})
 })
diff --git a/src/write/heosCommand.ts b/src/write/heosCommand.ts
index 80fbad6..578b97d 100644
--- a/src/write/heosCommand.ts
+++ b/src/write/heosCommand.ts
@@ -10,13 +10,7 @@ function attributeString(attributes?: HeosCommandAttribute): string {
 		return (
 			'?' +
 			Object.entries(attributes)
-				.map(([key, value]) => {
-					if (typeof value === 'string') {
-						return `${key}='${value}'`
-					} else {
-						return `${key}=${value.toString()}`
-					}
-				})
+				.map(([key, value]) => `${key}=${value}`)
 				.reduce((previous, current) => `${previous}&${current}`)
 		)
 	}