diff --git a/lib/rb/lib/thrift/protocol/tbinaryprotocol.rb b/lib/rb/lib/thrift/protocol/tbinaryprotocol.rb
index c8fa57d..a152bf2 100644
--- a/lib/rb/lib/thrift/protocol/tbinaryprotocol.rb
+++ b/lib/rb/lib/thrift/protocol/tbinaryprotocol.rb
@@ -20,7 +20,7 @@
   end
 
   def writeMessageBegin(name, type, seqid)
-    writeI32(VERSION_1 & type)
+    writeI32(VERSION_1 | type)
     writeString(name)
     writeI32(seqid)
   end