diff --git a/copy-to.js b/copy-to.js
index 6eefc36..716a072 100644
--- a/copy-to.js
+++ b/copy-to.js
@@ -9,7 +9,7 @@ var code = require('./message-formats')
 var CopyStreamQuery = function(text, options) {
   Transform.call(this, options)
   this.text = text
-  this._copyOutResponse = null
+  this._gotCopyOutResponse = false
   this.rowCount = 0
 }
 
@@ -30,50 +30,69 @@ CopyStreamQuery.prototype._detach = function() {
   this.connection.stream.resume()
 }
 
-
 CopyStreamQuery.prototype._transform = function(chunk, enc, cb) {
   var offset = 0
+  var Byte1Len = 1;
+  var Int32Len = 4;
   if(this._remainder && chunk) {
     chunk = Buffer.concat([this._remainder, chunk])
   }
-  if(!this._copyOutResponse) {
-    this._copyOutResponse = true
-    if(chunk[0] == code.ErrorResponse) {
-      this._detach()
-      this.push(null)
-      return cb();
-    }
-    if(chunk[0] != code.CopyOutResponse) {
-      this.emit('error', new Error('Expected CopyOutResponse code (H)'))
-    }
-    var length = chunk.readUInt32BE(1)
-    offset = 1
-    offset += length
-  }
-  while((chunk.length - offset) > 5) {
+
+  var length;
+  var messageCode;
+  var needPush = false;
+
+  while((chunk.length - offset) > (Byte1Len + Int32Len)) {
     var messageCode = chunk[offset]
-    //complete or error
-    if(messageCode == code.CopyDone || messageCode == code.ErrorResponse) {
-      this._detach()
-      this.push(null)
-      return cb();
-    }
-    //something bad happened
-    if(messageCode != code.CopyData) {
-      return this.emit('error', new Error('Expected CopyData code (d)'))
+
+    //console.log(c, w, offset, 'PostgreSQL message ' + String.fromCharCode(messageCode))
+    switch(messageCode) {
+
+      // detect COPY start
+      case code.CopyOutResponse:
+        if (!this._gotCopyOutResponse) {
+          this._gotCopyOutResponse = true
+        } else {
+          this.emit('error', new Error('Unexpected CopyOutResponse message (H)'))
+        }
+        break;
+
+      // meaningful row
+      case code.CopyData:
+        needPush = true;
+        break;
+
+      // standard interspersed messages. discard
+      case code.ParameterStatus:
+      case code.NoticeResponse:
+      case code.NotificationResponse:
+        break;
+  
+      case code.ErrorResponse:
+      case code.CopyDone:
+        this._detach()
+        this.push(null)
+        return cb();
+        break;
+      default:
+        this.emit('error', new Error('Unexpected PostgreSQL message ' + String.fromCharCode(messageCode)))
     }
-    var length = chunk.readUInt32BE(offset + 1) - 4 //subtract length of UInt32
-    //can we read the next row?
-    if(chunk.length > (offset + length + 5)) {
-      offset += 5
-      var slice = chunk.slice(offset, offset + length)
-      offset += length
-      this.push(slice)
-      this.rowCount++
+
+    length = chunk.readUInt32BE(offset+Byte1Len)
+    if(chunk.length > (offset + Byte1Len + length)) {
+      offset += Byte1Len + Int32Len
+      if (needPush) {
+        var row = chunk.slice(offset, offset + length - Int32Len)
+        this.rowCount++
+        this.push(row)
+      }
+      offset += (length - Int32Len)
     } else {
+      // we need more chunks for a complete message
       break;
     }
   }
+
   if(chunk.length - offset) {
     var slice = chunk.slice(offset)
     this._remainder = slice
diff --git a/index.js b/index.js
index 25e02c2..d6f0399 100644
--- a/index.js
+++ b/index.js
@@ -30,16 +30,18 @@ CopyStreamQuery.prototype.submit = function(connection) {
 
 var copyDataBuffer = Buffer([code.CopyData])
 CopyStreamQuery.prototype._transform = function(chunk, enc, cb) {
+  var Int32Len = 4;
   this.push(copyDataBuffer)
-  var lenBuffer = Buffer(4)
-  lenBuffer.writeUInt32BE(chunk.length + 4, 0)
+  var lenBuffer = Buffer(Int32Len)
+  lenBuffer.writeUInt32BE(chunk.length + Int32Len, 0)
   this.push(lenBuffer)
   this.push(chunk)
   cb()
 }
 
 CopyStreamQuery.prototype._flush = function(cb) {
-  var finBuffer = Buffer([code.CopyDone, 0, 0, 0, 4])
+  var Int32Len = 4;
+  var finBuffer = Buffer([code.CopyDone, 0, 0, 0, Int32Len])
   this.push(finBuffer)
   cb()
 }
diff --git a/message-formats.js b/message-formats.js
index 9827498..41325cc 100644
--- a/message-formats.js
+++ b/message-formats.js
@@ -7,11 +7,19 @@
  * https://www.postgresql.org/docs/current/static/protocol-flow.html
  */
 module.exports = {
-  ErrorResponse:    0x45,
-  CopyInResponse:   0x47,
-  CopyOutResponse:  0x48,
-  CopyBothResponse: 0x57,
-  CopyData:         0x64,
-  CopyDone:         0x63,
-  CopyFail:         0x66
+  ErrorResponse:        0x45, // E
+  CopyInResponse:       0x47, // G
+  CopyOutResponse:      0x48, // H
+  CopyBothResponse:     0x57, // W
+  CopyDone:             0x63, // c
+  CopyData:             0x64, // d
+  CopyFail:             0x66, // f
+
+  // It is possible for NoticeResponse and ParameterStatus messages to be interspersed between CopyData messages;
+  // frontends must handle these cases, and should be prepared for other asynchronous message types as well
+  // (see Section 50.2.6).
+  // Otherwise, any message type other than CopyData or CopyDone may be treated as terminating copy-out mode.
+  NotificationResponse: 0x41, // A
+  NoticeResponse:       0x4E, // N
+  ParameterStatus:      0x53  // S
 }