diff --git a/lib/protocol.js b/lib/protocol.js
index 4296cab..1040435 100644
--- a/lib/protocol.js
+++ b/lib/protocol.js
@@ -1275,8 +1275,10 @@ function createPacketBuffer(packetId, state, params, isServer) {
   offset = writeVarInt(packetId, buffer, offset);
   packet.forEach(function(fieldInfo) {
     var value = params[fieldInfo.name];
-    if(typeof value === "undefined") value = 0; // TODO : Why ?
-    offset = write(value, buffer, offset, fieldInfo, params);
+    if (!fieldInfo.condition || fieldInfo.condition(params)) {
+      if(typeof value === "undefined") value = 0; // TODO : Why ?
+      offset = write(value, buffer, offset, fieldInfo, params);
+    }
   });
   return buffer;
 }