diff --git a/lib/rex/proto/ntp/modes.rb b/lib/rex/proto/ntp/modes.rb
index c2a986ca58..f395340bb1 100644
--- a/lib/rex/proto/ntp/modes.rb
+++ b/lib/rex/proto/ntp/modes.rb
@@ -1,4 +1,8 @@
 # -*- coding: binary -*-
+
+require 'rubygems'
+require 'bit-struct'
+
 module Rex
 module Proto
 module NTP
@@ -25,7 +29,7 @@ module NTP
     unsigned :stratum, 8,  default: 0
     unsigned :poll, 8,  default: 0
     unsigned :precision, 8,  default: 0
-    char :payload, 352
+    rest :payload
   end
 
   # An NTP control message.  Control messages are only specified for NTP
@@ -62,11 +66,12 @@ module NTP
     #  0                   1                   2                   3
     #  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    # |00 | VN  |   7 |A|                   Sequence                  |
+    # |R M| VN  |   7 |A|                   Sequence                  |
     # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     # | Implementation| request code  |
     # +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
-    unsigned :reserved, 2, default: 0
+    unsigned :response, 1,  default: 0
+    unsigned :more, 1,  default: 0
     unsigned :version, 3,  default: 0
     unsigned :mode, 3,  default: 7
     unsigned :auth, 1, default: 0
diff --git a/modules/auxiliary/fuzzers/ntp/ntp_protocol_fuzzer.rb b/modules/auxiliary/fuzzers/ntp/ntp_protocol_fuzzer.rb
index 3ef1d896a5..bb67817de1 100644
--- a/modules/auxiliary/fuzzers/ntp/ntp_protocol_fuzzer.rb
+++ b/modules/auxiliary/fuzzers/ntp/ntp_protocol_fuzzer.rb
@@ -86,8 +86,8 @@ class Metasploit3 < Msf::Auxiliary
     check_and_set('MODE_7_REQUEST_CODES')
 
     connect_udp
-    fuzz_version_mode(ip)
     fuzz_version_mode(ip, true)
+    fuzz_version_mode(ip, false)
     fuzz_short(ip)
     fuzz_random(ip)
     fuzz_control(ip) if @modes.include?(6)
@@ -144,6 +144,7 @@ class Metasploit3 < Msf::Auxiliary
   def fuzz_random(host)
     print_status("#{host}:#{rport} fuzzing random messages")
     0.upto(5) do
+      # TODO: is there a better way to pick this size?  Should more than one be tried?
       request = SecureRandom.random_bytes(48)
       what = "random #{request.size}-byte message"
       vprint_status("#{host}:#{rport} probing with #{what}")
@@ -154,12 +155,17 @@ class Metasploit3 < Msf::Auxiliary
   end
 
   # Sends a series of different version + mode combinations
-  def fuzz_version_mode(host, short=false)
+  def fuzz_version_mode(host, short)
     print_status("#{host}:#{rport} fuzzing #{short ? 'short ' : nil}version and mode combinations")
     @versions.each do |version|
       @modes.each do |mode|
-        request = Rex::Proto::NTP.ntp_generic(version, mode)
-        request = request[0, 4] if short
+        request = Rex::Proto::NTP::NTPGeneric.new
+        request.version = version
+        request.mode = mode
+        unless short
+          # TODO: is there a better way to pick this size?  Should more than one be tried?
+          request.payload = SecureRandom.random_bytes(16)
+        end
         what = "#{request.size}-byte #{short ? 'short ' : nil}version #{version} mode #{mode} message"
         vprint_status("#{host}:#{rport} probing with #{what}")
         responses = probe(host, datastore['RPORT'].to_i, request)
diff --git a/spec/lib/rex/proto/ntp/modes_spec.rb b/spec/lib/rex/proto/ntp/modes_spec.rb
new file mode 100644
index 0000000000..b0e6a75b66
--- /dev/null
+++ b/spec/lib/rex/proto/ntp/modes_spec.rb
@@ -0,0 +1,83 @@
+# -*- coding: binary -*-
+#
+require 'rex/proto/ntp/modes'
+
+describe "Rex::Proto::NTP mode message handling" do
+  before do
+    @payload = 'R7' * 7
+  end
+
+  describe Rex::Proto::NTP::NTPControl do
+    before do
+      @control_raw = "\x1e\x05\x12\x34\x12\x34\x12\x34\x00\x00\x00\x0e" + @payload
+      @control = Rex::Proto::NTP::NTPControl.new
+      @control.version = 3
+      @control.response = 0
+      @control.more = 0
+      @control.operation = 5
+      @control.sequence = 0x1234
+      @control.association_id = 0x1234
+      @control.status = 0x1234
+      @control.payload_offset = 0
+      @control.payload_size = 14
+      @control.payload = @payload
+    end
+
+    it 'Generates control NTP messages correctly' do
+      @control_raw.should == @control.to_s
+    end
+
+    it 'Parses private NTP messages correctly' do
+      parsed_raw = Rex::Proto::NTP::NTPControl.new(@control_raw)
+      @control.should == parsed_raw
+    end
+  end
+
+  describe Rex::Proto::NTP::NTPGeneric do
+    before do
+      @generic_raw = "\xcc\x12\x34\x56" + @payload
+      @generic = Rex::Proto::NTP::NTPGeneric.new
+      @generic.li = 3
+      @generic.version = 1
+      @generic.mode = 4
+      @generic.stratum = 0x12
+      @generic.poll = 0x34
+      @generic.precision = 0x56
+      @generic.payload = @payload
+    end
+
+    it 'Generates generic NTP messages correctly' do
+      @generic_raw.should == @generic.to_s
+    end
+
+    it 'Parses private NTP messages correctly' do
+      parsed_raw = Rex::Proto::NTP::NTPGeneric.new(@generic_raw)
+      @generic.should == parsed_raw
+    end
+  end
+
+  describe Rex::Proto::NTP::NTPPrivate do
+    before do
+      @private_raw = "\x1f\x5a\x01\x99" + @payload
+      @private = Rex::Proto::NTP::NTPPrivate.new
+      @private.response = 0
+      @private.more = 0
+      @private.version = 3
+      @private.mode = 7
+      @private.auth = 0
+      @private.sequence = 90
+      @private.implementation = 1
+      @private.request_code = 153
+      @private.payload = @payload
+    end
+
+    it 'Generates private NTP messages correctly' do
+      @private_raw.should == @private.to_s
+    end
+
+    it 'Parses private NTP messages correctly' do
+      parsed_raw = Rex::Proto::NTP::NTPPrivate.new(@private_raw)
+      @private.should == parsed_raw
+    end
+  end
+end