lib/PublicInbox/DS.pm   | 6 +++---
 lib/PublicInbox/HTTP.pm | 2 +-
 lib/PublicInbox/NNTP.pm | 6 +++---

diff --git a/lib/PublicInbox/DS.pm b/lib/PublicInbox/DS.pm
index 01c8917eafedb6f509b0953ddf59c192b61ab86a..b7753e1a663148320e798aa606bfe0af1e9d4f7d 100644
--- a/lib/PublicInbox/DS.pm
+++ b/lib/PublicInbox/DS.pm
@@ -415,7 +415,7 @@     $written;
 }
 
 sub epbit ($$) { # (sock, default)
-    ref($_[0]) eq 'IO::Socket::SSL' ? PublicInbox::TLS::epollbit() : $_[1];
+	$_[0]->can('stop_SSL') ? PublicInbox::TLS::epollbit() : $_[1];
 }
 
 # returns 1 if done, 0 if incomplete
@@ -569,7 +569,7 @@     my $sock = $self->{sock} or return 1;
     my $wbuf = $self->{wbuf};
 
     if (MSG_MORE && (!defined($wbuf) || !scalar(@$wbuf)) &&
-		ref($sock) ne 'IO::Socket::SSL') {
+		!$sock->can('stop_SSL')) {
         my $n = send($sock, $_[1], MSG_MORE);
         if (defined $n) {
             my $nlen = bytes::length($_[1]) - $n;
@@ -619,7 +619,7 @@ # or fork w/o exec, so no inadvertent socket sharing
 sub shutdn ($) {
     my ($self) = @_;
     my $sock = $self->{sock} or return;
-    if (ref($sock) eq 'IO::Socket::SSL') {
+    if ($sock->can('stop_SSL')) {
         shutdn_tls_step($self);
     } else {
 	$self->close;
diff --git a/lib/PublicInbox/HTTP.pm b/lib/PublicInbox/HTTP.pm
index b73ce2d733500f9f38a540806200183301d99079..6ccf20592405e2ee3732d79283b8ac262c26cd6f 100644
--- a/lib/PublicInbox/HTTP.pm
+++ b/lib/PublicInbox/HTTP.pm
@@ -59,7 +59,7 @@ 	my ($class, $sock, $addr, $httpd) = @_;
 	my $self = fields::new($class);
 	my $ev = EPOLLIN;
 	my $wbuf;
-	if (ref($sock) eq 'IO::Socket::SSL' && !$sock->accept_SSL) {
+	if ($sock->can('accept_SSL') && !$sock->accept_SSL) {
 		return CORE::close($sock) if $! != EAGAIN;
 		$ev = PublicInbox::TLS::epollbit();
 		$wbuf = [ \&PublicInbox::DS::accept_tls_step ];
diff --git a/lib/PublicInbox/NNTP.pm b/lib/PublicInbox/NNTP.pm
index bffd773cf9eb087c5d990fed67db0da10e2ff345..be3bddc3f5d2a230642b4bf2dc878f7b6c5aec73 100644
--- a/lib/PublicInbox/NNTP.pm
+++ b/lib/PublicInbox/NNTP.pm
@@ -47,7 +47,7 @@ 	my ($class, $sock, $nntpd) = @_;
 	my $self = fields::new($class);
 	my $ev = EPOLLIN;
 	my $wbuf;
-	if (ref($sock) eq 'IO::Socket::SSL' && !$sock->accept_SSL) {
+	if ($sock->can('accept_SSL') && !$sock->accept_SSL) {
 		return CORE::close($sock) if $! != EAGAIN;
 		$ev = PublicInbox::TLS::epollbit();
 		$wbuf = [ \&PublicInbox::DS::accept_tls_step, \&greet ];
@@ -97,7 +97,7 @@ # The keyword argument is not used (rfc3977 5.2.2)
 sub cmd_capabilities ($;$) {
 	my ($self, undef) = @_;
 	my $res = $CAPABILITIES;
-	if (ref($self->{sock}) ne 'IO::Socket::SSL' &&
+	if (!$self->{sock}->can('accept_SSL') &&
 			$self->{nntpd}->{accept_tls}) {
 		$res .= "STARTTLS\r\n";
 	}
@@ -896,7 +896,7 @@ sub cmd_starttls ($) {
 	my ($self) = @_;
 	my $sock = $self->{sock} or return;
 	# RFC 4642 2.2.1
-	return r502 if (ref($sock) eq 'IO::Socket::SSL' || $self->compressed);
+	return r502 if ($sock->can('accept_SSL') || $self->compressed);
 	my $opt = $self->{nntpd}->{accept_tls} or
 		return '580 can not initiate TLS negotiation';
 	res($self, '382 Continue with TLS negotiation');