diff --git a/lib/producer_record.js b/lib/producer_record.js
index 214e647..df2a14a 100644
--- a/lib/producer_record.js
+++ b/lib/producer_record.js
@@ -36,7 +36,7 @@ ProducerRecord.prototype.validate = function validate() {
     if (typeof self.value !== 'string' && !Buffer.isBuffer(self.value)) {
         return new Error('ProducerRecord value is neither string nor byte array');
     }
-    if (self.key !== undefined && typeof self.value !== 'string') {
+    if (self.key !== undefined && typeof self.key !== 'string' && !Buffer.isBuffer(self.key)) {
         return new Error('ProducerRecord value is neither string');
     }
     return null;