diff --git a/lib/request.js b/lib/request.js
index 2a0ae903..9d435e98 100644
--- a/lib/request.js
+++ b/lib/request.js
@@ -50,13 +50,16 @@ const request = (ctx, userAgent, reqData) => {
 	})
 
 	if (profile.addChecksum || profile.addMicMac) {
-		if (!Buffer.isBuffer(profile.salt)) {
-			throw new TypeError('profile.salt must be a Buffer.')
+		if (!Buffer.isBuffer(profile.salt) && 'string' !== typeof profile.salt) {
+			throw new TypeError('profile.salt must be a Buffer or a string.')
 		}
+		// Buffer.from(buf, 'hex') just returns buf
+		const salt = Buffer.from(profile.salt, 'hex')
+
 		if (profile.addChecksum) {
 			const checksum = md5(Buffer.concat([
 				Buffer.from(req.body, 'utf8'),
-				profile.salt
+				salt,
 			]))
 			req.query.checksum = checksum.toString('hex')
 		}
@@ -65,7 +68,7 @@ const request = (ctx, userAgent, reqData) => {
 			req.query.mic = mic.toString('hex')
 
 			const micAsHex = Buffer.from(mic.toString('hex'), 'utf8')
-			const mac = md5(Buffer.concat([micAsHex, profile.salt]))
+			const mac = md5(Buffer.concat([micAsHex, salt]))
 			req.query.mac = mac.toString('hex')
 		}
 	}