diff --git a/lib/websocket/protocol.rb b/lib/websocket/protocol.rb
index 019e388..ab25c07 100644
--- a/lib/websocket/protocol.rb
+++ b/lib/websocket/protocol.rb
@@ -85,7 +85,7 @@ module WebSocket
       false
     end
 
-    def close
+    def close(reason = nil, code = nil)
       return false unless @ready_state == 1
       @ready_state = 3
       dispatch(:onclose, CloseEvent.new(nil, nil))
@@ -142,7 +142,7 @@ module WebSocket
     def self.server(socket, options = {})
       env = socket.env
       if env['HTTP_SEC_WEBSOCKET_VERSION']
-        Hybi.new(socket, options)
+        Hybi.new(socket, options.merge(:require_masking => true))
       elsif env['HTTP_SEC_WEBSOCKET_KEY1']
         Draft76.new(socket, options)
       else
diff --git a/lib/websocket/protocol/hybi.rb b/lib/websocket/protocol/hybi.rb
index 70b7ae3..a71cdbc 100644
--- a/lib/websocket/protocol/hybi.rb
+++ b/lib/websocket/protocol/hybi.rb
@@ -51,7 +51,8 @@ module WebSocket
         @protocols = options[:protocols]
         @protocols = @protocols.strip.split(/\s*,\s*/) if String === @protocols
 
-        @ping_callbacks = {}
+        @require_masking = options[:require_masking]
+        @ping_callbacks  = {}
       end
 
       def version
@@ -161,13 +162,16 @@ module WebSocket
       end
 
       def close(reason = nil, code = nil)
+        reason ||= ''
+        code   ||= ERRORS[:normal_closure]
+
         case @ready_state
           when 0 then
             @ready_state = 3
-            dispatch(:onclose, CloseEvent.new(code || 1000, reason || ''))
+            dispatch(:onclose, CloseEvent.new(code, reason))
             true
           when 1 then
-            frame(reason || '', :close, code || ERRORS[:normal_closure])
+            frame(reason, :close, code)
             @ready_state = 2
             true
           else
@@ -206,6 +210,9 @@ module WebSocket
       end
 
       def shutdown(code, reason)
+        code   ||= ERRORS[:normal_closure]
+        reason ||= ''
+
         frame(reason, :close, code)
         @ready_state = 3
         dispatch(:onclose, CloseEvent.new(code, reason))
@@ -238,6 +245,8 @@ module WebSocket
 
       def parse_length(data)
         @masked = (data & MASK) == MASK
+        return shutdown(ERRORS[:unacceptable], nil) if @require_masking and not @masked
+
         @length = (data & LENGTH)
 
         if @length <= 125
diff --git a/spec/websocket/protocol/hybi_spec.rb b/spec/websocket/protocol/hybi_spec.rb
index 05012b6..2e21977 100644
--- a/spec/websocket/protocol/hybi_spec.rb
+++ b/spec/websocket/protocol/hybi_spec.rb
@@ -223,7 +223,7 @@ describe WebSocket::Protocol::Hybi do
       it "closes the socket if the frame has an unrecognized opcode" do
         protocol.parse [0x83, 0x00]
         @bytes.should == [0x88, 0x02, 0x03, 0xea]
-        @close.should == [1002, nil]
+        @close.should == [1002, ""]
         protocol.state.should == :closed
       end
 
@@ -357,6 +357,23 @@ describe WebSocket::Protocol::Hybi do
     end
   end
 
+  describe "when masking is required" do
+    before do
+      options[:require_masking] = true
+      protocol.start
+    end
+
+    it "does not emit a message" do
+      protocol.parse [0x81, 0x05, 0x48, 0x65, 0x6c, 0x6c, 0x6f]
+      @messages.should == nil
+    end
+
+    it "returns an error" do
+      protocol.parse [0x81, 0x05, 0x48, 0x65, 0x6c, 0x6c, 0x6f]
+      @close.should == [1003, ""]
+    end
+  end
+
   describe "in the :closing state" do
     before do
       protocol.start