diff --git a/util/TLSProxy/ClientHello.pm b/util/TLSProxy/ClientHello.pm
index 383062842..0586cf9a5 100644
--- a/util/TLSProxy/ClientHello.pm
+++ b/util/TLSProxy/ClientHello.pm
@@ -55,7 +55,8 @@ use strict;
 
 package TLSProxy::ClientHello;
 
-use parent 'TLSProxy::Message';
+use vars '@ISA';
+push @ISA, 'TLSProxy::Message';
 
 sub new
 {
diff --git a/util/TLSProxy/NewSessionTicket.pm b/util/TLSProxy/NewSessionTicket.pm
index 75dbf2323..4e8c71381 100644
--- a/util/TLSProxy/NewSessionTicket.pm
+++ b/util/TLSProxy/NewSessionTicket.pm
@@ -54,7 +54,8 @@ use strict;
 
 package TLSProxy::NewSessionTicket;
 
-use parent 'TLSProxy::Message';
+use vars '@ISA';
+push @ISA, 'TLSProxy::Message';
 
 sub new
 {
diff --git a/util/TLSProxy/ServerHello.pm b/util/TLSProxy/ServerHello.pm
index 7cf753508..4798f2214 100644
--- a/util/TLSProxy/ServerHello.pm
+++ b/util/TLSProxy/ServerHello.pm
@@ -55,7 +55,8 @@ use strict;
 
 package TLSProxy::ServerHello;
 
-use parent 'TLSProxy::Message';
+use vars '@ISA';
+push @ISA, 'TLSProxy::Message';
 
 sub new
 {
diff --git a/util/TLSProxy/ServerKeyExchange.pm b/util/TLSProxy/ServerKeyExchange.pm
index b85b8addc..a3973be96 100644
--- a/util/TLSProxy/ServerKeyExchange.pm
+++ b/util/TLSProxy/ServerKeyExchange.pm
@@ -55,7 +55,8 @@ use strict;
 
 package TLSProxy::ServerKeyExchange;
 
-use parent 'TLSProxy::Message';
+use vars '@ISA';
+push @ISA, 'TLSProxy::Message';
 
 sub new
 {
diff --git a/util/dofile.pl b/util/dofile.pl
index 76dfe2b60..78b8dfed9 100644
--- a/util/dofile.pl
+++ b/util/dofile.pl
@@ -35,7 +35,9 @@ use File::Spec::Functions;
 use lib catdir(dirname(__FILE__));
 use with_fallback qw(Text::Template);
 
-use parent qw/Text::Template/;
+#use parent qw/Text::Template/;
+use vars qw/@ISA/;
+push @ISA, qw/Text::Template/;
 
 # Override constructor
 sub new {