diff --git a/lib/perl/lib/Thrift/Protocol.pm b/lib/perl/lib/Thrift/Protocol.pm
index e2801fe..3e9f0dd 100644
--- a/lib/perl/lib/Thrift/Protocol.pm
+++ b/lib/perl/lib/Thrift/Protocol.pm
@@ -34,6 +34,9 @@
 use constant NEGATIVE_SIZE => 2;
 use constant SIZE_LIMIT    => 3;
 use constant BAD_VERSION   => 4;
+use constant NOT_IMPLEMENTED => 5;
+use constant DEPTH_LIMIT   => 6;
+
 
 sub new {
     my $classname = shift;