diff --git a/lib/protocol/protocol.js b/lib/protocol/protocol.js
index 52d32062..7568eb66 100644
--- a/lib/protocol/protocol.js
+++ b/lib/protocol/protocol.js
@@ -378,7 +378,7 @@ function encodeMessage(message) {
 
     var value = message.value;
 
-    if (value !== null) {
+    if (value !== null && value !== undefined) {
         if (Buffer.isBuffer(value)) {
             m.Int32BE(value.length);
         } else {