diff --git a/encode.js b/encode.js
index d0aa06f..3be3324 100644
--- a/encode.js
+++ b/encode.js
@@ -119,6 +119,8 @@ State.prototype.record = function(section_name, record) {
 
     // Write the rdata. Update the position now (the rdata length value) in case self.encode() runs.
     var match, rdata
+    if(record.data === null)
+      return
     switch (record.class + ' ' + record.type) {
       case 'IN A':
         rdata = record.data || ''
diff --git a/message.js b/message.js
index 7d5a2fc..3c85f74 100644
--- a/message.js
+++ b/message.js
@@ -118,7 +118,7 @@ DNSMessage.prototype.toBinary = function() {
 
     msg[section] = msg[section] || []
     msg[section].forEach(function(record) {
-      if(record.class != 'IN')
+      if(record.class != 'IN' || record.data === null)
         return
 
       // Make sure records promising data have data.